Sept. 2, 2020 -- Every year since 2010, the CDC has urged almost all Americans over 6 months old to get a flu shot. And every year we fall far short -- just half of us got vaccinated during the 2018-19 season. One reason: Some people believe the shot just doesn’t work.

Because flu viruses mutate constantly and the vaccine wears off over time, you can’t get vaccinated once and expect to be covered for years, as you can with other diseases. The vaccine must be changed each year, in hopes of matching the ever-mutating viruses. And that’s been a challenge. On average, it’s been 40% effective, meaning it’s prevented illness 40% of the time. Since health officials started tracking it in 2003, effectiveness has varied from year to year, ranging from a low of 10% in 2004-05 to a high of 60% in 2010-11.

Coronavirus in Context: CDC Director Discusses Next Steps in the War Against COVIDWebMD's Chief Medical Officer, John Whyte, speaks with Robert Redfield, MD, Director, Centers for Disease Control and Prevention (CDC), about next steps in the war against COVID.1141


JOHN WHYTE: You're watching

Coronavirus in Context.

I'm Dr. John Whyte,

chief medical officer at WebMD.

Today, I'm joined by Dr. Robert

Redfield, the director

of the Centers

for Disease Control

and Prevention.

Dr. Redfield, thanks for joining




Thanks for having me.

JOHN WHYTE: You're a virologist

by training.

What has surprised you

about this novel coronavirus?

ROBERT REDFIELD: Well, you know,

I think that it's important

that we don't really know

this virus very well.

We just got introduced about

seven months ago.

I think the things that

surprised us the most--

me the most--

was how infectious this virus


You know, when we saw that it

was a coronavirus,

I think we were thinking it was

going to be more like SARS

or MERS.

Or even with the first cases

we identified in the US,

the first 12 cases

that we did contact tracing

in over 850 people, we only

found two of those contacts, who

were infected both spouses.

So we-- we had a view

that this virus was probably

going to be more like MERS

and SARS, but we rapidly

understood that this is a highly

infectious disease.

And I think that's probably

the first thing that surprised


And the second thing

is that, probably for a majority

of individuals under the age

of 50, it's disproportionately


And I think those were the two

things that we learned.

I wish we had been invited

in early.

I had asked my counterpart

George Gao, you know, to have us

come join in back on January 3,

to put CDC in to work

alongside him, to try

to understand the outbreak as it

was unfolding in Wuhan.

You know, I think if we had been

able to get in at that time,

we probably would've learned

quicker than we learned here

that, in fact, it is highly

infectious and two,

that asymptomatic disease is

going to be a critical hallmark

of this infection.

JOHN WHYTE: While we're

at 5 million cases.

But as you know, to put it

in perspective

for our listeners,

we're at 4 million cases

roughly, you know, three weeks


So the trajectory in terms

of the number of new cases

is higher than we would like.

How do you think we got to 5


Is it people aren't doing

the safeguards that they need

to be doing?

Are people not taking it


I was told you're in one

of the old war rooms

in the old executive office


How are we doing in this war

against COVID 19?


you're right.

It is a war.

I think the first thing that I'd

like to say

is that we're pretty

confident that this virus slowly

entered the United States

in late January and February.

And there wasn't

extensive infection

throughout February.

We have about five

different lines of evidence

to support that conclusion

that we've published.

But clearly in March, there

started to be more introduction,

particularly from Europe

and basically ceded large parts

of the United States.

When we looked at March, April,

and May, we had about 2 million

infections that were diagnosed,

as you alluded to.

What's interesting, we went back

and do antibody testing

during that period.

We actually had evidence

that, for every one case that

was diagnosed,

there was actually 10 more


Probably in those first three

months, we actually had

20 million people in.

But if you divide 20 million

by 90 days,

you can see that we're looking

at probably over 200,000

infections a day

even though we were only

recognizing 10,000 or 15,000.

JOHN WHYTE: Dr. Redfield, we're

over 160,000 deaths

in the United States so far.

Do you expect COVID to be

a leading cause of death

by the end of the year?

ROBERT REDFIELD: You know, John,

I think it's-- it's clearly

going to be one of them.

If you looked back and used

our surveillance systems that we

have-- and we have one

that looks death by pneumonia.

And we had either pneumonia,

influenza like illness,

or COVID like illness.

And they really all probably

represented COVID.

At one point in time in April,

early May, 27% of all deaths

in the United States

was caused by pneumonia,

influenza, or a COVID like.

So clearly-- and I can show you

the curve-- a huge spike

when this outbreak hit New York

and then the follow up deaths.

So it's clearly going to be

a major cause of death

in the United States.

Luckily, the mortality

is improving really for two


One is we're recognizing more

infections, so the denominator

is different.

But also we really are getting

better as physicians

and managing these patients.

Good recognition

of the hypercoagulable state.

The importance

of anticoagulation.

The recognition that steroids

has a role in advanced disease.

The earlier ability to use


So the mortality, I think,

continues to decline.


We've also changed ventilator

protocols as well.

We're not treating it as much as


ROBERT REDFIELD: Very important,

that the agent in ventilator

protocols, as you know.

And I think we've learned a lot

in escalations--

I'm an internist too--

and how to manage

these patients.

And hopefully, we'll

see on the horizon not too


we'll see

additional new therapeutics come

into add to the armamentarium

that clinicians have.

So-- and eventually this virus

is going to have its day.

It's either going to infect

a majority

of the global population,

or we're going to have

a biological countermeasure,

that's going to be

an effective vaccine, that's

going to prevent it

from affecting [INAUDIBLE].

JOHN WHYTE: [? We only hope. ?]

Let's talk about vaccines.

But first I want to talk

about the flu vaccine.

And you've been talking about

and cautioning how important it

is, especially this year,

to get the flu vaccine as we

fight COVID.

Last year, you know, roughly not

even 50% of those

that should I've gotten the flu

vaccine received it.

How do you think we're going

to do better this year?

And remind viewers why it's

so important this year.


is really important.

And I've said if there's

one thing we all can

do besides the importance

of wearing a mask,

social distancing,

hand washing, and be

smart about gatherings-- that

basically ultimately prepare

ourselves, for the fall,

to get the flu vaccine.

As you mentioned, about 47%

people got the flu vaccine.

JOHN WHYTE: CDC often recommends

the goal is 60% to 70%.

ROBERT REDFIELD: That's right.

Yeah, my goal this year

was to get it up to 65%.

And I think one of the messages

we're trying to do

is that really switch it

from the anti vax or vaccine


that the campaign of

to vaccinate with confidence.

You know, and trying to tell

the American public, please

don't leave

this important accomplishment

of American medicine

on the shelf for yourself,

your family, your church, your--

your workforce.

By getting vaccinated,

you can protect your children.

Clearly, when we look

at the mortality

that we see with flu, one thing

is for certain.

The kids who get vaccinated,

they basically get protected

against death.

It also has an impact

on the rest of us

in terms of severity of illness

and hospitalization.

Some people don't realize.

In the last 10 years,

360,000 people died

in this country from flu.

Flu is a major cause of death.

We have

a biological countermeasure

and a vaccine, and we do have


And this is the year I'm asking

people to really think deep down

about getting the flu vaccine.

We've worked with industry.

Industry is plussing up

the amount of vaccine they're

going to make available.

So probably over close to 100

million doses this year.

190 million doses.

The CDC and myself, we've

purchased an extra 10 million


Normally, we only purchase about

500,000 doses

for uninsured adults

to give to the States.

This year, I've purchase

10 million doses

for uninsured adults

of the States

to make sure States can get

this flu vaccine now.

And the real reason is we're

going to have COVID in the fall,

and we're going to have flu

in the fall.

And either one of those

by themselves

can stress certain hospital


I've seen hospital

intensive care units stretch

by a severe flu season,

and clearly, we've all seen it

recently with COVID.

So by getting that flu vaccine,

you may be able to then negate

the necessity to have to take up

a hospital bed.

And then that hospital bed

can be more available for those

that potentially get

hospitalized for COVID.

JOHN WHYTE: Let's talk

about the COVID vaccine.

How optimistic are you

that we'll see a vaccine early

next year?

And can you give us a better

sense of time frame?

As you know, Russia announced

today, Sputnik V, their vaccine

is approved while they're still

in phase two.

So how realistic

is it that we're going to have

something January, February?

Or are we thinking more later

first quarter?


cautiously optimistic that we're

going to have one or more

vaccines deployed

before the first of the year.

Right now, this operation work


I'm on the board of it.

I've been in vaccine development

all my life.

And the [INAUDIBLE] plus years

I've spent in the military

at Walter Reed

and then at the University

of Maryland, I've never seen

vaccine development move

like this.

There's actually a very


private public partnership

with the private sector.

And there's six vaccines now

that are moving forward

extremely rapidly.

Three of which now are already

in phase III trials.

And I suspect there'll

be a fourth.

So very optimistic that we're

going to have one or more

vaccines available.

I want people to realize,

since we're going so fast,

some people worry about we're

cutting corners.

And really there's

no scientific integrity to cut--

corners being cut.

There's no corner cut

for safety.

The corner that we're cutting

is the investment in being

able to make the vaccine.

So when companies are

ready for phase III trials,

the US government started

production of 100 million doses

of the vaccine,

as if it was going to work.

JOHN WHYTE: But in fairness

and timelines, we're in August.

You know, some of the industry

had 5,000.

They still need 25,000 more

participants to, you know,

reach their phase III


People still have to catch

the virus, right?

And then we have a control group

that we have to compare to.

So the timeline is pretty

compressed if we're thinking

of something by the end

of the year.

Isn't that right?

Early next year and then it

still has to be reviewed.

ROBERT REDFIELD: Very quickly,

if there's any light to the fact

of the sudden surge

and the challenge of all

the new cases we're having is,

you know, a number of the trial

sites are up and running.

They started two weeks ago.

They're enrolling very rapidly.

I do think they'll all have

their enrollment done

between now

and the end of September.

And, uh-- and then we'll

see what the data shows.

The other thing I want to say

that's so different and so


here is, unlike the trials

that you may have been involved

with, and I know I was involved

with, we're not excluding

the elderly.

JOHN WHYTE: That's right.


actually get in the trial

if you're 65 or 70-year-olds.

We're not excluding people

with diabetes, and obesity,

and heart disease,

which normally don't get

in trial.

We're not excluding pregnancy.

So the high risk individuals,

that we're hoping this vaccine

is used for, are being included

in these phase III trials,

so we can determine whether it's

potentially going to have

a immunogenicity and safety

in the population at most risk.

Because that's really where we

want to get this vaccine as

quick as possible.

JOHN WHYTE: My understanding was

that there aren't anyone

enrolled under age 18.

Is that right?


[? there. ?]

The current trials have not

included children.

That doesn't mean there's not

going to be companion trials.

But now all the trials over 18.

But unlike many of them

that I've been involved

in the past that don't enroll

people over the age 45,

this one's enrolling people

all the way up to over 70.


with multiple medical illnesses.

So they'll have to be follow-up

trials for children

under the age of 18,

but clearly, there's

a comprehensive trial right now

that will accommodate the people

that are either most at risk

because of comorbidities and age

or are most at risk because

of their jobs.

You know, there are physicians,

nurses, intensivists, et cetera.

JOHN WHYTE: What does

Thanksgiving look

like this year, Dr. Redfield?


it is a moment of Thanksgiving.

You know-- you know,

this whole thing started for me

on New Year's Eve.

And I can say it's been--

it's just been all hands on deck

since then

when I got my first call

about the new mysterious

pneumonia in China

on December 31.

Clearly, it's almost a tale

of two cities.

If the American public will

really take to heart what I've


wear a mask,

the social distance,

to use great hand--

hand hygiene, and to be

smart about crowds,

and we all do that.

And I keep telling people,

I'm not asking some of America

to do it.

We all got to do it.

This is one

of those interventions that got

to be 95%, 96%, 97%, 98%, 99%,

if it's going to work for us.

JOHN WHYTE: Why can't we get

people to wear masks?

It seems like a small price.


to keep trying.

We've got to keep trying.

You know, I was-- it's


It's very

different in different cities.

You know, I was recently

in an area where I--

you know, three, four,

five-year-olds were all wearing

their masks.

Every-- all the parents.

I didn't see anybody

without a mask.

But I've been in other areas

where it's the opposite.

We really do need to get

the mask really does work.

It's really important.

So when you ask me what

Thanksgiving's going to be like,

I think it's just

dependent upon how

the American people choose

to respond.

We're going to continue to try

to do what we can to be


In-- in speaking,

I've said before, when John

Kennedy said, "don't ask what

your country can do.

Ask for what you can do

for your country."

Kind of try to paraphrase that.

For your country right now

and for the war that we're

in against COVID, I'm asking you

to do four simple things.

Wear a mask, social distance,

wash your hands,

and be smart about crowds.

You do those four things,

it will bring this outbreak


But if we don't do that, as I

said last April,

this could be the worst fall

from a public health

perspective, we've ever had.

JOHN WHYTE: Tell us what you

miss, Dr. Redfield.

Is it you miss traveling?

How has this impacted you



when I decided to accept

the opportunity to be the CDC


I had to give up something

that I really love dearly,

and that's the practice

of medicine.

I've cared for with some

of my patients

with HIV for more than 25 years.

In a way, I'm looking forward

to, when my tour of duty

is over,

get back to the practice

of medicine, because I truly

love practicing medicine.

At CDC, I think what's really

is the intensity of what we're


You know, love someone

like yourself

to get into the agency

and see how much is going on.

I mean, there are thousands

and thousands of people working

24/7 on this pandemic.

And the fact is that really all

of our focus

is on this pandemic right now.

I have

other important initiatives.

Ending the AIDS epidemic

in America, that the president

started, that we're still

committed to, you know.

But obviously, some

of that effort gets sidetracked.

Getting tobacco use in children.

All the progress we've made

with these cigarettes.

Want to get that back on.

Making progress

on maternal mortality.

You know, there's no reason why

700 to 800 mothers have to die

in this country

every year giving birth

to babies.

JOHN WHYTE: Women of color


ROBERT REDFIELD: That's right.

And the progress that we're

trying to make in getting people

treated for hepatitis C, virus

with diabetes.

So there's a lot of programs.

And when you look

at the collateral damage

of the COVID, it is that we've

all had to turn our focus


I tell my colleagues at CDC,

please, you know, do

the extra effort to keep

the main programs you're doing

moving forward,

which is not a time to lose


You know, I think the last seven

months have been just,

just as you said before, we're

kind of in a war.

I will say we're in a war.

And I hope people realize,

and one of the things

I recognized when I became

the director, we really haven't

invested, in this nation,

in the core capabilities

of public health.

It's always been something

we left,

you know, for leftovers.

And hopefully, I've tried

to make the argument.

Now is the time to invest

in public health.

Data, data analytics,

predictive data analysis,

laboratory resilience

in our public health labs,

public health workforce.

You know, we have some states

that we're down to less than 40,

30, 20 contact tracers.

And then, of course, we need

to have the emergency resources

to operationalize that

with a global footprint,

and hopefully pick these things

up where they start,

and to put them out

before they become here.

That's one of my hopes

that we'll take from this

is that people now realize

that public health matters.

This nation is going to spend

somewhere between $3, 4, 5, 6,

7 trillion

in responding to this pandemic.

And I do think if--

if-- if we could make

that investment

in those core capabilities, data

lab people.

And make sure we do it

for the whole nation.

I think many people may not

realize CDC is the background

funding for the public health

infrastructure of every city

and every state in this nation.

We need to over-invest.

Get over-prepared.

I will say that--

that in four or five decades

of investment when

this-- when the big one came.

And this is not a minor one.

This is the greatest

public health crisis that hit

this nation in a century.

That we were under-prepared.

And we need to owe it

to our children

and grandchildren

that this nation is never

under-prepared again

for a public health crisis.

JOHN WHYTE: Well, Dr. Redfield,

I want to thank you and all

of your colleagues

at CDC for working tirelessly

to protect us, you know,

during this time

of the pandemic.

And I hope we can check in

with you to discuss some

of those other priorities,

that that CDC is working on,

to really protect and advance

the health of Americans.

And as you said, really refocus

and invest in public health

and public health strategies.

Thank you.

ROBERT REDFIELD: Thank you very


We look forward to that.

God bless.


John Whyte, MD, MPH. Chief Medical Officer, WebMD, <br>Robert Redfield, MD, Director, Centers for Disease Control and Prevention (CDC)/delivery/aws/dd/69/dd69ddcb-7c98-3993-88bd-ab7bae911a19/Redfield_081120_,4500k,2500k,1000k,750k,400k,.mp408/12/2020 09:37:0018001200Redfield_081120_1800x1200/webmd/consumer_assets/site_images/article_thumbnails/video/covid19-images/Redfield_081120_1800x1200.jpg091e9c5e81f9d5c1

Here’s what makes it so difficult. There’s no single flu virus. It comes in several strains, the two most common being A and B. The A strain, the more dangerous of the two, has two subtypes that spread regularly among humans: A(H1N1) and A(H3N2). And the B strain, which tends to cause a milder illness, gets classified into two lines. From there, each one branches out further as new mutations occur.

“When we talk about building an influenza vaccine, we’re not just trying to make a vaccine for one virus, like with the measles,” says Michael L. Jackson, PhD, the principal investigator for the United States Influenza Vaccine Effectiveness Network from Kaiser Permanente Washington Health Research Institute. “We’re trying to make a vaccine for four different viruses all at once.”

Vaccines for A and B viruses were first given in the 1940s. In 1947, investigators realized that mutations in the viruses had made the vaccine ineffective, setting in motion the annual system we have now. Five years after that, the World Health Organization (WHO) established the Global Influenza Surveillance and Response System, which monitors the changes in the predominant flu viruses circulating each year.

Today, more than 100 countries gather information about the flu year-round. The WHO collates that information and spearheads the effort to predict which flu viruses will dominate in the coming year. Each new vaccine includes one A(H1N1), one A(H3N2), and one or two B viruses. For the Northern Hemisphere, those predictions take place in February -- that’s right, while the current flu season is still in full swing, scientists must determine what should be in the vaccine for the next season.

That’s because making the vaccine takes time -- drugmakers need at least 6 months to produce enough doses. Flu viruses mutate quickly, and sometimes by the time the vaccine is ready, a circulating virus has changed, says Jeffrey Shaman, PhD, a professor at the Columbia University Mailman School of Public Health who leads the development of the school’s flu forecasting system. “So what actually comes out in the vaccine is not quite what they intended,” he says.

Another problem: Since they’re working so far ahead, sometimes the virus predictions simply miss the mark. “The majority of the time we get it right, but from time to time we get it wrong,” says Jackson.

How We Track Effectiveness

The U.S. Flu Vaccine Effectiveness Networks began collecting data during the 2003-2004 flu season. Before then, how well the vaccine worked wasn’t routinely monitored. The networks include three groups of hospitals and universities, each focused on a different part of the vaccine’s effectiveness.

At the University of Michigan School of Public Health, Joshua Petrie, PhD, is part of a team that works with the CDC’s U.S. Flu Vaccine Effectiveness Networks. The program recruits patients from outpatient clinics who come in because of a respiratory illness that might be related to the flu. Tests determine whether or not each patient has the flu, and researchers like Petrie compare the proportion that are vaccinated in those who tested positive to those who tested negative. “If the vaccine works well, we expect a higher proportion of negative people to be vaccinated,” he says.

The data gathered by the various networks gets adjusted to account for differences in age, race, and medical conditions, then researchers determine the estimated effectiveness each year.

If the Vaccine Isn’t Always Effective, Why Get One?

The flu is a serious illness. When the viruses in the vaccine are a good match with what’s circulating, the vaccine can reduce your risk of having the flu by 40%-60%. And even when the match isn’t great, being vaccinated before you get the flu can help you avoid having a severe case. Numerous studies have shown that the vaccine cuts your risk of having to go to the hospital -- and if you are hospitalized, you’re much less likely to be admitted to the intensive care unit.

The Truth About the Flu ShotSkeptical of whether flu shots are safe or worthwhile? Here’s what you should know.79

SPEAKER: Wondering

whether the flu shot is

safe or worthwhile?

Here's the truth.

Can it give you the flu?


Some shots contain viruses that

are weakened, but they can't

cause an infection.

You could have some soreness

at the injection site, muscle

aches, or a mild fever


These are just reactions

your body makes

to a foreign substance entering


Serious side effects are rare,


Does the shot really work?


Some years it's more

effective than others.

But it always boosts your odds

of staying healthy through flu


Should you really get the shot

every year?


Different strains of the virus

could be going around.

Each year, the vaccine protects

you from three or four strains

that scientists think will be

the most common.

And your protection

from your previous vaccine

wears off over time.

Can it give my child autism?


Numerous studies have found

no link between vaccines

and autism.

However, there are

life-threatening risks

associated with the flu,

like pneumonia.

Getting your child a flu shot

is the best way to protect them

from that.

The bottom line is that the flu

shot is safe for almost everyone

six months old or older.

Your doctor may have you skip it

if you've ever had a severe

allergic reaction to the vaccine

or if you have a rare disorder

called Guillain-Barré syndrome.

CDC: “Key Facts About Seasonal Flu Vaccine,” “Misconceptions about Seasonal Flu and Flu Vaccines,” “Who Should NOT Get Vaccinated with these Vaccines?” American Lung Association: “Myths and Facts about the Flu Shot.” Harvard: “10 Flu Myths.” Mayo Clinic: “Guillain-Barre syndrome.” Pond5. AudioJungle./delivery/98/be/98be4370-c93e-4cca-ab6e-fcb15853d94d/truth-about-the-flu-shot_,4500k,2500k,1000k,400k,750k,.mp410/18/2018 10:13:00650350flu shot/webmd/consumer_assets/site_images/article_thumbnails/video/truth_about_the_flu_shot_video/650x350_truth_about_the_flu_shot_video.jpg091e9c5e81b013d2

According to the CDC’s estimates for the 2018-19 season, vaccinating only half of all Americans prevented 4.4 million cases of the flu, 58,000 hospitalizations, and 3,500 deaths. That was in a year that the vaccine was only 29% effective.

“Even with a less-than-perfect vaccine, there can still be big results in terms of prevented illnesses and severe outcomes,” says Petrie.

For children, the vaccine can be life-saving: A study of four flu seasons found that vaccination reduced the risk of death by half for kids with other conditions, and by almost two-thirds among healthy kids.

“We almost never know ahead of time whether we’ve guessed correctly or not. We can’t say, ‘This year it’s only going to be 10% effective, so don’t get it,’” says Jackson. “But the vaccine is relatively low-cost, with rare side effects, and reducing the risk of hospitalization and death by 50% is better than nothing.”

And much like wearing a mask helps protect those around you from the coronavirus, getting a flu shot may also help safeguard others who are more vulnerable to a severe case, like the very young and old and those with some chronic health conditions.

Improving the Flu Vaccine

Researchers are working to make the vaccine more effective on two fronts. Some are looking for ways to produce the annual vaccine more quickly, which would give scientists more time to pinpoint exactly which viruses to include. The longer they can wait, the more likely they are to make an accurate prediction.

Until 2013, all flu vaccines were made by growing samples of the viruses in fertilized chicken eggs, which required not only an enormous number of eggs but also lots of time. And growing the virus in eggs can introduce changes to it, which can make the vaccine less effective. But now, two other technologies can grow the virus faster.

Cell-based vaccines grow samples of the virus in cultured animal cells, which can take less time than using eggs. (The savings vary, but it starts with the fact that the cells are kept frozen in cell banks, so manufacturing doesn’t have to wait for a large supply of eggs.) And recombinant vaccines don’t need a sample at all. They use DNA to create a synthetic version of the viruses. Right now, there’s only one cell-based flu vaccine and one recombinant flu vaccine approved by the FDA. For the 2020-21 flu season, the CDC expects 81% of the vaccine supply to be egg-based.

The other way we could see an improvement is a bit of a vaccination holy grail: A universal flu vaccine, one that could provide long-lasting protection against many types of the virus. This would stop the need for a new version of the vaccine each year. Researchers have been working for years to create a vaccine that targets a stable portion of the virus -- one that doesn’t mutate. Several possible universal vaccines are in clinical trials right now, including three that have reached phase III, where the vaccine is given to thousands of people and tested to make sure it works and is safe.

"We're on the cusp of a universal flu vaccine," Amesh Adalja, MD, an infectious diseases specialist and senior scholar at Johns Hopkins Center for Health Security in Baltimore, told LiveScience. "It's long been a joke that a universal flu vaccine is always 5 years away. But I think, this time, it really is coming within the next 5 years."

WebMD Health News


National Library of Medicine: “Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010.”

CDC: “2018-19 Influenza Illnesses, Medical Visits, Hospitalizations, and Deaths Averted by Vaccination,” “Misconceptions about Seasonal Flu and Flu Vaccines,” “Vaccine Effectiveness: How Well Do the Flu Vaccines Work?” “CDC Seasonal Flu Vaccine Effectiveness Studies,” “Past Seasons Vaccine Effectiveness Estimates,” “Influenza Historic Timeline,” “Types of Influenza Viruses,” “Selecting Viruses for the Seasonal Influenza Vaccine,” “CDC Study Finds Flu Vaccine Saves Children’s Lives,” “How Influenza (Flu) Vaccines Are Made,” “Seasonal Influenza Vaccine Supply for the U.S. 2020-2021 Influenza Season.”

National Opinion Research Center (NORC) at the University of Chicago: “37% of Americans Do Not Plan to Get a Flu Shot This Season.”

Joshua Petrie, PhD, research investigator, Department of Epidemiology, University of Michigan School of Public Health.

Michael L. Jackson, PhD, associate investigator, Kaiser Permanente Washington Health Research Institute.

Jeffrey Shaman, PhD, professor, environmental health sciences, and director, climate and health program, Columbia University Mailman School of Public Health.

American Society for Microbiology: “A Universal Influenza Vaccine: How Close Are We?”

LiveScience: “Scientists may be 'on the cusp' of a universal flu vaccine.”

© 2020 WebMD, LLC. All rights reserved.