What We Learned from Chickens

Enter the chickens.

Read was studying vaccines that could combat malaria when he got interested in Marek’s disease, a highly contagious viral disease that affects chickens.

It’s a form of herpes that is found in chicken dander and is more virulent than the Ebola virus, Read said.

After experiments done in a specialized pathogen-containment facility at The Pirbright Institute in the United Kingdom, the researchers concluded that the vaccines developed to combat Marek’s disease were imperfect or leaky.

“These vaccines also allow the virulent virus to continue evolving precisely because they allow the vaccinated individuals, and therefore themselves, to survive,” said Venugopal Nair, who led the research team. He is the head of the Avian Viral Diseases program at The Pirbright Institute.

These less-than-perfect vaccines create a “leaky” barrier against the virus. Vaccinated individuals may get sick but have less severe symptoms, but the virus survives long enough to transmit to others, which allows it to survive and spread throughout a population.

“Our research demonstrates that the use of leaky vaccines can promote the evolution of nastier ‘hot’ viral strains that put unvaccinated individuals at greater risk,” Nair said.

Marek’s disease used to be a minor ailment that did little harm to chickens in the 1950s, but the virus has grown stronger and today is capable of killing all the unvaccinated birds in poultry flocks, sometimes within 10 days.

But since nearly every chicken in agricultural production throughout the world is vaccinated, Marek’s is a relatively minor problem today.

Read More: Vaccine for High Blood Pressure May Be in the Works »

Preventing More-Virulent Virus Strains

Marek’s is not the only nasty disease out there. The virus causing avian influenza can be even deadlier.

“The most virulent strain of avian influenza now decimating poultry flocks worldwide can kill unvaccinated birds in just under three days,” Read said, because the vaccine against avian influenza is a leaky one.

“In the United States and Europe, the birds that get avian influenza are culled, so no further evolution of the virus is possible,” Read said.

Culling is a more expensive process than using a leaky vaccine, he said. But it’s safer.

“Instead of controlling the disease by culling infected birds, farmers in Southeast Asia use vaccines that leak — so evolution of the avian influenza virus toward greater virulence could happen,” he added.

Some human deaths from avian influenza virus have been reported in China.

“We now are entering an era when we are starting to develop next-generation vaccines that are ‘leaky’ because they are for diseases that do not do a good job of producing strong natural immunity — diseases like HIV and malaria,” Read said.

What’s the answer?

Rigorous testing and vigilant monitoring of next-generation vaccines to prevent the evolution of more-virulent strains of viruses will help.

Read sees this as crucial to the current attempt to develop an Ebola vaccine. He notes that secondary techniques can help when using leaky vaccines, such as insecticide-treated bed nets for prevention of malaria.

Read More: Researchers Closer to HIV Vaccine Than Ever Before »

20 questions and answers about the flu vaccine

In order to address flu concerns and help readers make decisions for themselves and their families, our FindCare team helped compile a list of 20 common concerns about flu vaccination from friends, family, and online forums. Six doctors and epidemiologists answered these questions based on their expertise.

Read on to learn more about how flu vaccination works and why health experts consider getting one so important.

1. How is the flu vaccine made?

Flu experts at more than 100 influenza centers around the world keep track of the different flu variations, or strains, and go through an intensive research process to identify which strains may be the most common in a given season.

This research process helps create a flu vaccine that’s specific to the common flu strains expected that winter.

However, flu viruses vary every year, and this means some flu seasons are worse, and some years the flu vaccine may be less effective.

2. How does the flu shot work?

Emily Temple-Wood, DO, family medicine resident at Lutheran General Hospital said, “I like to think of the flu shot — and vaccines in general — as target practice for your body.”

“Our immune systems are infinitely adaptable, but the main downside is that it takes time for them to learn how to fight different bugs, which means you usually get sick the first time you get exposed to something like the flu,” she said. “We can hack that system with vaccines, which give your body the information it needs to fight something off without getting you sick.”

Antibodies are what the body uses to fight infections, and they get stronger when you’ve already been exposed to a virus.

“So, if you’ve had the flu shot and get coughed on by someone who has the flu, your immune system has already seen the flu and has practiced killing it. That means that if you get sick at all, it’ll be less severe,” said Temple-Wood.

3. Can you get the flu from the flu vaccine?

Temple-Wood explained that the flu shot is an inactivated or “killed” virus vaccine, which means you can’t get sick from the shot.

“When you get the shot, your immune system makes antibodies against the dead viruses, and these antibodies protect you from being infected by the live virus,” she said.

Jessica Malaty Rivera, MS, infectious disease researcher and science communication lead at the COVID Tracking Project agreed: “No, you cannot get the flu from the flu vaccine.”

Even the nasal spray flu vaccine — which contains live, but weakened, virus — will not cause the flu.

Rivera added, “For those who are vaccinated against flu and still get the flu during flu season, symptoms are often milder as a result of vaccination.”

4. What side effects should I expect?

Lindsey Shultz, MD, public health analyst and expert contributor to COVID-19 explained, “The most common side effects for the injected vaccine are tenderness, redness, or a bit of swelling at the injection site.”

“While not everyone will get these,” she said, “it’s good to plan ahead for a few days of muscle soreness in whichever arm you get the vaccination, just in case. So figure out which arm will work out best for you — most people pick their nondominant arm.”

Shultz warned that it’s also possible to develop a low-grade fever, headache, or nausea, but she explained that these symptoms should go away after a day or two.

“The nasal spray flu vaccine also has the potential to cause a runny nose, sore throat, and cough,” she said.

“Serious adverse events are quite rare, and the risk profile is much lower than the risks you’d generally run from getting the flu itself,” Shultz said.

“Contact your medical provider if you experience a high fever or signs of a severe allergic reaction like difficulty breathing, dizziness, or a rapid heartbeat. These signs would most likely happen within a few minutes to hours of getting the shot and can be remedied with medical treatment,” said Shultz.

5. Why is my arm sore after I get my flu shot?

Temple-Wood explained that your arm gets sore after a flu shot for a couple of reasons.

“The first one is that you got stabbed a little bit and any kind of poke hurts. The second reason is that your immune system is busy mustering that response to the killed viruses in the vaccine. This involves sending white blood cells to the area and increasing blood flow, which causes swelling as well,” she said.

Temple-Wood added that the best way to reduce or prevent pain or swelling at the injection site is to relax your arm as much as possible while you’re getting your flu shot.

It also helps to move your arm more afterward to get lymphatic flow moving. You can also use heat or cold packs, and over-the-counter pain medications if the pain is severe and your doctor says it’s OK.

6. I got sick once after getting the flu shot, why should I get it again?

Josh Petrie, PhD, assistant professor at the University of Maryland School of Public Health said, “Many types of viruses cause cold and flu-like symptoms, but the flu shot only protects against the influenza virus, which typically causes more severe disease.”

Getting vaccinated is the best way to protect yourself and others from influenza.

“You cannot get influenza from a flu shot, but it is not uncommon to feel a little under the weather after receiving it. That means your immune system is responding to the vaccine and is a good thing,” said Petrie.

7. Can I get vaccinated if I don’t like needles?

Rachel Roper, PhD, associate professor at the East Carolina University Medical School said, “Yes, there is a flu mist nasal vaccine. The flu injection/shot is a killed (dead) virus, but the flu nasal spray vaccine is a live attenuated virus. It is a severely weakened virus that will cause a small brief infection in your nasal passages. Most people don’t even notice it.”

Because the flu nasal vaccine is a live virus, people who have conditions that affect their immune systems may not be able to take it.

Roper said the flu nasal spray has been approved for healthy people 2–49 years old, but there’s actually a CDC-approved listTrusted Source of people who shouldn’t get the live flu mist vaccine.

8. How do I get vaccinated if I don’t have health insurance?

“Without insurance, the out-of-pocket cost will typically be around $40 for the regular dose, with an added cost for a senior dose,” said Shultz.

She recommended checking with services like Blink Health or GoodRx to see if any discounts are available in your area, and VaccineFinder can help you locate pharmacies near you.

“There are also a number of options that provide free or discounted shots. Some schools and workplaces will hold events offering a flu shot to all members of their communities. Most county health departments also offer free or significantly discounted vaccines for people without insurance or could provide you with more information about where to go in your community,” said Shultz.

9. When is the best time to get vaccinated?

“The best time to get vaccinated is whenever you can — though October seems to be a pretty good sweet spot for staying protected through the end of flu season, earlier is totally OK, too,” said Temple-Wood.

“Definitely don’t wait if you have the opportunity!” she said. “There’s no such thing as too late, either. If you’re being offered the flu shot, it’s because there’s still flu hanging around.”

10. Where should I go to get a flu shot?

Roper said you can get a flu shot at your doctor’s office, public health clinics, many pharmacies, and even some grocery stores.

She recommends that everyone has a primary care physician for things like vaccines and common illnesses.

“If you have a physician, you can get help when you need it. If you don’t have a physician, it can be really difficult to find an appointment when you need one. Just go make an appointment with a physician for a check-up and flu shot so you will have an existing relationship with one where they have your info on file. It could save your life,” said Roper.

11. Should my young children also get flu shots?

Allison Messina, MD, chairman of the division of infectious disease at Johns Hopkins All Children’s Hospital said, “Yes, flu shots are recommended for all children aged 6 months and older. The youngest age recommended is 6 months.”

According to the CDC, children are at risk of serious complications from the flu like pneumonia, dehydration, brain swelling, and though rare, death.

That’s why it’s so important to have children vaccinated. It also helps prevent missed days from school and the risk of hospitalization.

12. Why is the flu vaccine less effective some years?

“Flu vaccine effectiveness can vary from season to season,” Rivera said. “The protection provided depends on the similarity between the viruses in the vaccine and those in circulation, as well as the health of the individual.”

She explained that there are different strains or types of flu viruses, and flu vaccines usually work better against influenza A (H1N1) and influenza B. The vaccine may be less effective against influenza A (H3N2).

“During seasons when the vaccine is well-matched [to the virus], vaccination can reduce the risk of flu illness by up to 60 percent,” she said.

13. Why do I need to get a vaccine every year?

Viruses change because the genes for that virus change. Some viruses change very little and others, like influenza, change frequently and sometimes in many genes.

Roper explained, “Influenza viruses belong to the orthomyxovirus family of viruses. They are very unusual because they have eight different genome segments, eight different pieces. Most viruses have one piece of genome, but flu has eight.”

“Because of this, flu can ‘reassort’ genome pieces with other related viruses and make a whole new strain. This happens frequently, every year, so we have to make a whole new vaccine each year because the flu genome changes so dramatically,” Roper said.

“Other viruses that have one genome piece slowly mutate and evolve over time,” Roper added. “That’s why our vaccines for measles, mumps, rubella, and chickenpox have worked for decades — because those viruses mutate more slowly.”

14. I’m young and healthy. Do I still need to get vaccinated?

“Yes! In a normal flu season, hospitalizations can overwhelm our healthcare system, and this year we have a global pandemic, so it is especially important for everyone to get vaccinated,” Roper said.

“You don’t want to have a flu problem and have to go to a doctor or emergency room that is packed with COVID-19 patients,” Roper added. “This could expose you to unnecessary risks, plus overwhelm the nurses and doctors trying to care for all the patients.”

According to the CDC, between 12,000 and 61,000 deathsTrusted Source have occurred annually in the United States from influenza since 2010.

That’s why getting a flu vaccine is so important. While most COVID-19 and flu deaths are in people over age 50, there are still deaths in children and even people in their 20s and 30s.

15. Should you get vaccinated if you’re pregnant or breastfeeding?

“Yes, pregnant and breastfeeding women should be vaccinated for flu. Pregnant women should get the injectable flu vaccine rather than the intranasal one,” said Messina.

Pregnant people are at greater risk of serious illness caused by the flu.

Flu symptoms like high fever can affect the fetus as well.

Getting a flu shot during pregnancy can also protect a newborn from flu after birth because the mother passes her antibodies to the baby through the placenta.

16. If I’ve already had the flu, should I still get vaccinated that same year?

“Flu season typically starts in October and goes through March,” Rivera said. “If you got the flu before October, you are still vulnerable to the upcoming flu season and should get vaccinated.”

She also noted that if you got the flu during the current flu season, you could still be vulnerable to other strains of the flu circulating that season and should still get a flu shot.

17. I never get the flu! Why should I get the vaccine?

Temple-Wood warned, “You’ve never gotten the flu until you get the flu, yanno? There’s a first time for everything, and that includes the flu.”

She explained that even if you don’t get the flu, are in good health, or don’t get particularly sick when you have had the flu, there may be vulnerable people around you.

People with chronic health conditions, babies, pregnant people, and older people are all at risk. “People who have recovered from COVID-19 are likely particularly vulnerable to the flu this year as well,” she said.

18. I’m already wearing a mask and socially distancing. Why do I need a vaccine?

“Unfortunately, as we have seen, no preventive measures are foolproof. They instead act likely overlapping layers of protection. The more risk-reducing choices we make, the safer we keep ourselves, our families, and our communities,” said Shultz.

“Just like wearing a mask helps keep others safe, getting a flu vaccine not only helps keep you safe, but also the vulnerable people around you who either can’t get a flu vaccine or those in whom they may not work as well,” Shultz added.

Shultz also said getting a flu shot helps your local medical system by keeping local emergency rooms, waiting rooms, and doctor’s offices available for people with COVID-19 as the pandemic continues into winter.

19. Is the flu shot effective at preventing COVID-19?

No, a flu shot will not protect you from COVID-19. Currently, there’s no vaccine against COVID-19.

“Influenza and coronavirus are two different virus families so a flu vaccine cannot prevent COVID-19,” Rivera said. “There is also no evidence that getting a flu vaccine increases the risk of getting COVID-19.”

20. Was this year’s vaccine “phoned in” because scientists are working on COVID-19?

Not at all. This year’s vaccine is getting as much attention as any other year.

According to Petrie, “No, the normal procedures for selecting vaccine virus strains and manufacturing vaccines have been in place. The World Health Organization (WHO) selected which virus strains to include in the Northern Hemisphere vaccine at the end of February, and vaccine manufacturers are projecting that they will have more doses available than in the past.”