Vaccines and infection

What will happen if the vaccines are no longer effective against the new variants?


We know that SARS-CoV-2 viruses will continue to evolve. Some new virus variants may be associated with biological advantages eventually leading to higher transmissibility, disease severity, risk of reinfection, or a change in antigenic target of vaccines resulting in lower vaccine effectiveness. But this will not happen suddenly, meaning that vaccine-induced protection is wide and includes both humoral and cellular response. The S protein -the antigen contained in the vaccines- is large, and thus, elicits a wide array of neutralizing antibodies. However, once a critical number of mutations accumulates in the receptor binding domain of the S protein, the neutralizing capacity of the vaccine may get compromised.

WHO and partners are undertaking a coordinated approach to monitor and evaluate variants and their impact on vaccine effectiveness.

We need to do everything we can to reduce circulation of the virus and delay mutations that may reduce the efficacy of existing vaccines. The virus only evolves through replication and thus, prevention of infection with all available means will reduce the chances that escape variants emerge. Nevertheless, it seems increasingly clear that manufacturers will have, and are ready, to adjust to the COVID-19 viral evolution, taking into account the latest variants for future vaccine developments or booster shots.