Last year, only 17% of Americans got a fall Covid booster.

So far this year, it's under 3%, per Bloomberg.

In a dire worst-case scenario, an expedited campaign for variant-specific booster shots would be a more effective means of saving lives compared to an annual autumn vaccination. According to Florian Krammer, creating a new mRNA vaccine tailored to a specific variant is technologically feasible within a span of two months. In late 2021, the world experienced significant outbreaks when the Omicron variant emerged. Krammer highlighted that having an Omicron-specific vaccine available in January 2022 would have been immensely beneficial. However, what transpired was a bivalent vaccine introduced in September, directed at a waning Omicron sub-variant.

In the absence of a dangerous new variant, administering an annual shot to everyone may not be the most efficient approach. The initial vaccines provided robust protection against severe illness by stimulating the production of immune cells stored in bone marrow, which could last for years. The evidence suggests that the first booster may have enhanced this long-term immunity. In this context, Krammer views the third shot more as an extension of the primary vaccination series than a conventional booster.

However, additional doses do not significantly enhance long-term immunity. Any protection they confer against current variants relies on circulating antibodies, which begin to diminish within approximately three months and experience a steep decline by about nine months.

While it is conceivable that scientists could create a more potent vaccine designed to shield against potential new variants, as well as mild infections, the challenge lies in reduced funding. Compared to the substantial resources available during Operation Warp Speed, it could now take years to develop a working vaccine, as per Krammer. The pharmaceutical industry's investment may dwindle as well due to declining demand. Pfizer, for example, recently acknowledged that demand for its boosters and the antiviral medication, Paxlovid, fell significantly below their forecasts.

Monica Gandhi, an infectious disease specialist at the University of California San Francisco, underscored the importance of Krammer's paper in highlighting future risks. Given the virus's rapid evolution, constantly updating vaccines to match circulating variants is a challenging and potentially futile endeavor. She suggests adhering to the World Health Organization's guidance, which prioritizes booster doses for those most susceptible to severe illness, as the primary objective is to protect against severe disease. Mass vaccination campaigns should be reserved for the eventuality of a more hazardous variant.