We Cannot ‘Boost Our Way Out’ Of The Covid Pandemic, Experts Warn
U.S. officials greenlit second booster doses of the Pfizer-BioNTech and Moderna Covid vaccines last week in an effort to bolster waning immunity ahead of a potential surge of cases driven by the infectious BA.2 omicron subvariant, but experts question whether everyone even needs a fourth shot or if regular boosting is a sustainable strategy to manage the coronavirus long-term.
The Food and Drug Administration on Tuesday authorized a second booster shot of Moderna's and Pfizer's Covid-19 vaccine for people ages 50 and older, citing data indicating waning immunity months after the first booster dose and increased protection against serious disease for older age groups.
While a fourth dose appears to be beneficial at preventing serious illness in older or high-risk people, Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, told Forbes that repeated boosting is not "a viable strategy" and it's not clear that younger groups without high-risk health conditions "benefit much from even third doses."
With growing evidence of rapidly fading immunity against omicron after three to four months of getting the third dose of an mRNA vaccine from Moderna and Pfizer, Professor Dan Barouch, a vaccine researcher at Harvard Medical School, told Forbes that boosting every three to six months is not "practical" for wealthy countries.
For poorer countries, frequent boosting is "simply not possible," Barouch said, adding that "vaccines with better durability are needed."
"It's not sustainable," echoed Professor Deepta Bhattacharya, an immunologist at the University of Arizona, who said we need "more bang for the buck from these vaccines."
Bhattacharya said we could buy a lot more time between booster shots if they're updated to match circulating variants, as all vaccines in widespread use are still based on the original strain of coronavirus.
WHAT TO WATCH FOR
New vaccines. Most major Covid vaccine makers-including Pfizer, Moderna, Johnson & Johnson and Novavax-are working on omicron-specific shots to address fading effectiveness against the variant. "The sooner we can get them updated, the better," Bhattacharya said. By the time these vaccines are available, however, the worst of omicron could very well be behind us and another variant have taken its place. AstraZeneca, for example, only ditched efforts to create a beta-specific vaccine in February, long after the variant had stopped being one of the most concerning forms of the virus. Even with mRNA vaccines-relatively quick to produce and swift to edit-simply retooling vaccines to counter the latest variant can be far too slow and leaves a vulnerable period as it is produced, tested, cleared, manufactured and distributed. Dr. John Swartzberg, an infectious disease expert at the University of California at Berkeley, told Forbes he hopes we will find a way to make the vaccine give long-lasting immunity against "all current and future variants." Such a long-lasting pan-coronavirus vaccine "is a realistic hope," he said. Several efforts are underway to create a universal vaccine-which would target parts of the virus crucial to its function and don't change across variants-including an initiative by the U.S. Army.
"I don't think we can simply boost our way out of the pandemic," Weill Cornell Medicine professor of microbiology and immunology John P. Moore told Forbes in an email. "A lot depends on the pandemic's trajectory," he explained. Moore pointed to "complex questions that need to be addressed over time" including whether there will be new and different waves, how long any wave might last and how we emphasize protection against infection versus protection against serious illness in the future.
Not all experts think updated vaccines are needed right now. Moore told Forbes the shots based on the virus can still be used for a "long time yet," describing the case for variant based vaccines as "weak," based on available data. Moore said animal studies show that beta, delta and omicron boosters were little or no better than boosting with the original vaccine, adding that few unvaccinated people are likely to change their minds and get the shot "solely because the vaccine composition changes." An omicron-specific vaccine would also do little to protect previously unvaccinated people if a more "traditional" variant like delta reappears, he said. Swartzberg also said it is "not clear at this point that we need to update our current vaccine," noting evidence that the "'older' vaccine gives broad-based immunity."
The U.S. has joined a growing number of countries-including the U.K., Sweden, Israel and Denmark-offering second booster doses to at-risk groups. In Israel, experts advising the government have recommended making fourth doses available to all adults. While frequent booster shots using existing or novel formulations are common for some diseases like flu or tetanus, the practice of successive boosting with Covid has been developed in real time; initial vaccine trials were not able to assess how durable the protection a vaccine provided was beyond a few months. Data now suggests that the Johnson & Johnson vaccine, originally considered the least effective of those available in the U.S., is now preventing infections and serious illness as well as, if not better than, Moderna and Pfizer shots. Adalja told Forbes it's important to remember the primary goals of vaccination: preventing serious illness, hospitalization and death, not stopping infection. When it comes to this goal, studies assessing immunity based on antibodies do not capture the full picture and other parts of the immune system like T cells can still help prevent serious illness even if they cannot stop infection.