Several highly effective vaccines were developed at an unprecedented speed to combat the COVID-19 pandemic. During the phase 3 clinical trials, mRNA vaccines had vaccine efficacy of 94–95% in preventing symptomatic infections. After the rollout, real-world evidence showed that the mRNA vaccines provided ~90% effectiveness against infection. Then came the variants. The wave after wave of new variants, with ever-increasing transmissibility and capacity to escape existing immunity, challenge the ability of vaccines to prevent infection and transmission. The effectiveness of a primary series of mRNA vaccines (two doses) to prevent hospitalization and death is also being chipped away by these highly immune-evasive variants.
Vaccine-mediated protection became shorter-lived, especially with the emergence of Omicron variants. People look at these data and wonder, what is the point of getting the vaccines if they will not prevent symptomatic infections, and the protection does not last? Well, to expect robust protection from just the primary series of any vaccines is unreasonable—and was always likely to be—but somehow society has placed too high a bar on what is considered an acceptable number of doses for COVID-19 vaccines. Instead, we need to understand that we’re going to be getting boosters in the foreseeable future, and to appreciate their benefits.