The COVID-19 vaccine manufactured by Moderna is the second to receive the green light from a panel of experts set to advise the Food and Drug Administration (FDA).
On Thursday afternoon, a 19-member committee unanimously voted to recommend that the FDA recommend booster syringes for people previously vaccinated with Moderna’s COVID-19 vaccine. It is now up to the FDA to make a final decision which the Centers for Disease Control (CDC) Advisory Committee on Immunization Practices will consider shortly to work out the final recommendation on who should receive the Moderna booster.
Moderna succeeds Pfizer-BioNTech, which received FDA approval for its booster in September. The CDC followed suit with a booster recommendation for anyone over 65 years of age who had received their last Pfizer BioNTech vaccine dose at least six months previously; and anyone ages 18 to 64 who are more prone to complications from COVID-19 because of underlying health conditions or because they work in a higher-risk environment such as a hospital, grocery store, or school.
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The Advisory Committee unanimously voted for a moderna vaccine refresh; However, in a post-vote discussion, members raised concerns about whether the data the committee and FDA have reviewed so far is sufficient to justify boosters for the wider population. Several committee members expressed their support for a booster dose for vulnerable populations, including those over 65 and those with compromised immune systems who are at higher risk of developing severe COVID-19 and its complications, but noted the lack of data supporting the benefits prove in younger people, even in jobs that could expose them to risk. Still, members voted to recommend the Moderna shot for a population that mirrors that currently eligible for the Pfizer BioNTech booster. (The same FDA committee had voted against the recommendation of the Pfizer BioNTech booster for these groups, but CDC Director Dr. Rochelle Walensky decided to include them so that those in high-risk situations could have an additional dose obtain.)
In particular, the committee members lacked risk-benefit data that clearly showed that a Moderna booster dose would offer additional protection to younger people who develop adequate immune responses after the first injections. In fact, FDA scientists presenting to the committee stressed that immunity to the original two doses is still strong enough to protect most people from getting sick enough to be hospitalized or from receiving them COVID-19 die. So many committee members questioned the reasons for extending the booster recommendation to younger people with otherwise healthy immune systems. “It is clear that older people benefit from this,” said Dr. Paul Offitt, committee member and professor of pediatrics at Philadelphia Children’s Hospital. “But I’m less impressed with data on the younger person. I worry that widespread use of the booster without clear evidence of benefit would send the wrong message …
Offit pointed out that regulators and public health officials have not made it clear what the vaccine’s goal is. Initially, it seemed that vaccines were recommended to protect people from severe COVID-19 illness, but the urge to booster vaccinations for everyone seems to shift the goal towards infection prevention – which vaccines are not as effective and not the standard were with which they were initially tested.
The “booster for everyone” argument also includes the idea that boosters may be needed to maintain an adequate immune response over the longer term, like a gas tank that needs to be refilled regularly. However, there is not enough information to know whether this makes sense because vaccine manufacturers have not provided sufficient data on the duration of immune responses and how their vaccinations are protected.
Dr. Patrick Moore, another committee member and professor at the University of Pittsburgh Cancer Institute, said he voted for the booster “more on gut instinct than on really serious data. The data itself isn’t strong, however [is] certainly go in the direction that supports this vote. “
Moderna presented data from a complicated study of 300 people who were randomly given either two regular doses or two half doses of the vaccine. All were then given a booster dose of half the dose and the researchers recorded their antibody levels up to six months later. The company tested how well these people’s blood produced antibodies to both the original SARS-CoV-2 virus, against which the vaccines were developed, and the Delta variant, and compared these levels to those of people who received participated in a previous study of people who received the two-dose vaccine but did not receive a booster dose. The results, according to Moderna, showed that the half-dose booster reawakened the immune system enough to quickly produce antibodies against SARS-CoV-2, as it was already prepared for it with the two previous doses, and that halving the dose did Double the number of people who could be vaccinated with the extra vaccine while reducing the frequency of potential side effects. However, the committee noted that the number of people examined – although technically large enough to consider authorization for emergency use – was quite small and the data may not be fully representative of what could happen if hundreds of Millions of people get a refresher.
To provide context for the possible effects of booster doses, the committee also heard from experts from Israel, which was among the first countries to successfully vaccinate a large portion of its adult population with the original two doses of the Pfizer BioNTech vaccine, and started seeing breakthrough infections in some of the elderly who were vaccinated the earliest. Israeli health authorities approved booster doses in August; Dr. Sharon Alroy, director of the Israeli Ministry of Health’s public health service, presented data showing that people who received this booster had a much lower rate of breakthrough infections and were less likely to be hospitalized or die of COVID-19 than those who received it didn’t do. In fact, Alroy Price attributes the booster program, which started with people over 65 but now includes most people over 16, to lower the national incidence of new COVID-19 cases.
“For me there is no question that we will [rising] Curve of cases due to the booster dose, ”she said. “We are now coming out of our fourth wave and without the booster I fear that it would have put us in a worse place with a high case load for hospitals with severe, critical patients. The booster dose allowed us to get out of that wave. ”However, Israel relied primarily on the Pfizer BioNTech vaccine, so some panelists questioned the applicability of the Israeli experience to the Moderna booster debate, despite the vaccines made in the same way using mRNA technology.
From the discussions about the booster, it became clear that scientists’ understanding of COVID-19 immunity still has major gaps. Experts still don’t know exactly what kind of immunity is needed to protect people from infection – what antibodies are needed to fight off SARS-CoV-2? How long do these antibodies last? Do the vaccines produce enough of these antibodies? – which means they still can’t really tell how useful or needed booster doses will be for most of us.
For now, however, regulators and public health executives assume that in a pandemic emergency, you will pull out all the stops and provide every means to protect people, even if the benefits are not overwhelming.
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Reference: time.com
