The Biden administration announced this week that it will begin providing COVID booster shots for most Americans eight months after they have received their second doses of Modernas messengerRNA (mRNA), or Pfizers vaccines. People will begin receiving boosters in September 20th, subject to approval from the U.S. Food and Drug Administration and Centers for Disease Control and Preventions vaccine advisor panel. Nursing home residents and health care workers will be the first to receive boosters.
Scientists have been debating the need for such boosters, when and who to administer them. The announcement was made less than a month after the CDC suggested that moderately and severely immunocompromised patients should be given an additional shot. This was because there had been evidence that they might not be able to mount an adequate response to two doses. Based on data from Israel, vaccine manufacturers and several U.S. studies that showed that vaccine-induced immunity against COVID waned after six months and that vaccines are less effective in preventing mild or moderate diseases from the coronavirus' notorious Delta variant than earlier strains, the latest recommendation was made. However, two doses of the mRNA vaccinations appear to be sufficient to protect against death and severe disease.
Waiting for something to happen ..., will leave you behind in your true responsive ..., capability, said Anthony Fauci (chief medical advisor to President Joe Biden), during a White House press conference on Wednesday. You want to be ahead of the virus.
Experts are not all convinced that boosters will be needed for most people. The World Health Organization said that it was unethical for rich countries not to give shots to people who have been vaccinated, even though a large portion of the world's population has yet to be given a dose. The Biden administration has however defended their decision, stating that the U.S. government shouldn't have to choose between protecting itself and protecting the rest. Experts also believe that more shots would be more effective in protecting the population than giving booster shots to people who have been vaccinated.
Scientific American reached out to Shane Crotty (virologist, professor at La Jolla Institute for Immunology) and Cline Gounder (infectious disease specialist, epidemiologist, NYU, Bellevue Hospital, New York City, member of the Biden–Harris Transition COVID-19 Board), for information about booster shots and other questions.
[A transcript of the interview is available.]
Are booster shots necessary? Who is the most in need of booster shots?
GOUNDER - The data show that vaccines are still highly protective against severe diseases, hospitalizations, and death, even if they are against the Delta variant. We are not seeing an increase in death and hospitalization. We are actually seeing a decrease in immunity to the Delta variant of infection.
It is obvious that these people should receive additional doses. Some people will not respond to the extra dose, but others may. People in nursing homes can also get the virus. We have seen cases of severe illness and death from these people. Nursing homes can be infected by unvaccinated caregivers. Although it makes sense to give more doses to residents of nursing homes, you will likely have a greater impact if the caregivers are also given them. There is no evidence to support the administration of additional doses to the general population in the U.S.
CROTTY - It all comes down to what the word "need" means. Different people mean different things. The past month has generated enough uncertainty over Delta and how long protection will last that I believe a government decision is reasonable to use boosters in a safer than sorry manner. It is not a good idea to rush the decision.
A booster is essential for immunocompromised patients. In May, June, and July there was data that showed many immunocompromised people who did not respond to two shots had better results with three. A clinical trial has shown that certain immunocompromised individuals can benefit from a third dose. After one to two doses, people who had positive T cells (a type of immune cell) had an antibody response that was strong to the third dose. Do boosters need to be given to people over 80? This makes perfect sense. We know that they are at high risk, but it is not that large. What about those over 70? 60? 50? These are policy decisions.
Is the immune response to vaccines good?
CROTTY - It appears that the vaccine creates high-quality immune memories. Science published a paper last week that showed antibodies six months after the second vaccination. There wasn't much of a decline. Six months after an mRNA vaccination (a low dose) of Moderna, we have made public the first data about T cell memory. Between one and six months, there was virtually no change in T-cell memory. It should last for at least one year. The data from England shows that there was a lot of Delta and that the vaccines were effective against it. The Delta wave had a huge difference in deaths and hospitalizations compared to the winter wave. This was when the Alpha variant was first identified in the U.K. Do boosters need to be used? For hospitalizations and deaths, no.
Will boosters work? Yes, according to Moderna clinical trial data and Pfizer data. They will increase antibody titers. But are they really necessary? Uncertain.
What are your thoughts on the Israeli data that suggests vaccine immunity declines over time?
CROTTY - The best data available on the vaccine waning is from Israel. However, Israeli officials have not published any [in a scientific publication]. I learn from epidemiologists. Confounding factors can be a problem. In February and March, Israel experienced a lot of problems with its vaccine efficacy. Finally, they published a paper proving that the vaccine was effective. It appears that the vaccine is showing a decline in effectiveness, and possibly a significant decline. It's possible, but we don't know.
GOUNDER : The Israel data has serious problems. They can be confounded by other factors and age. They should not be presented in PowerPoint slides, but the raw data. I wouldn't make decisions based solely on Israeli data.
Also, laboratory data can be problematic. The best indicator of protection is the so-called neutralizing antibody. It is not easy to determine if they are present six months or a year later. Your blood would be literally sludge if you had antibodies for every infection. It would be a completely different story if immune cells known as memory B or T cells disappeared. However, you can expect antibodies to decrease.
Can people who have received the Johnson & Johnson vaccination be given a booster?
CROTTY - I believe it is time for people who have had the Johnson & Johnson vaccination to receive a second dose. The Delta variant spreads faster than other strains. Data suggests that there is a decline in immunity to Delta. The Johnson & Johnson COVID-19 vaccine trial, which includes Delta variant cases in a 500,000-person study in South Africa, has just been published. The vaccine offers 93 percent protection against death and 71 percent protection against hospitalizations in Delta. This is consistent with the fact that people who have received one dose of Johnson & Johnson vaccine should be able to request a booster dose. [Editor's note: This answer was adapted to severalTwitter threads Crotty provided.
GOUNDER : Data from a clinical study comparing low- versus high dose and single- versus double-dose Johnson & Johnson vaccines should be available soon. These data will guide recommendations on giving additional doses to Johnson & Johnson vaccine-eligible patients who have received one dose.
Mixing and matching vaccines is possible, for example, AstraZenecas or Johnson & Johnsons adenovirus vaccine plus an mRNA vaccination.
CROTTY. For those who received the viral vector vaccines (such as AstraZeneca, Johnson & Johnson vaccines), it is pretty obvious that a follow up dose of mRNA is more effective than a second dose. It also works better than two doses of AstraZeneca. Data supporting the mixing of vaccines date back at least 20 years. It is called a heterologous prim-boost. It is important to choose the right order. I wouldn't get Pfizer, then J&J. You could still get Pfizer, then J&J, and then a Protein Vaccine [a vaccine that contains fragments from SARS-CoV-2 proteins such as Novavax's, but has not been approved in the U.S.].
GOUNDER : Heterologous prime-boost is a topic that needs to be discussed more. An adenovirus vaccine, followed by an mRNA (or adenovirus), followed by a protein vaccination may be a good idea. Intranasal inhaled vaccinations should be considered. These would be more effective in initiating mucosal immunity (immunity in your nose and upper respiratory tract)
What side effects might a third shot cause? What might the side effects be if a third shot is administered?
GOUNDER: More of the same: mild fevers, fatigue, and achiness. These are not common for everyone.
Do booster shots need to be given to people who have been vaccinated, when the majority of the world remains unvaccinated?
CROTTY: It's a false dichotomy. You won't be able to move the vaccines around, as they are about to expire. It would be the best case scenario for the U.S. if all people who are not vaccinated were vaccinated. This would be much better than using boosters. It isn't even close.
GOUNDER - Clearly, giving people more doses is not going to make a difference. It is possible to have more impact on the community by reducing transmission [by vaccinating unvaccinated].
What frequency will boosters be needed? Is it just one booster or will we require one each year, like the flu shot.
GOUNDER - I hate the term booster, as it implies an annual vaccine. The COVID vaccine is most like the hepatitis B vaccination. An annual hepatitis B vaccination is not offered. It's about optimizing the dosing schedule, how many doses and at what spacing. It won't be yearly, I don't think. This virus could become an epidemic. This is a virus that can kill you or land you in the hospital.
