Vaccines and Variants
August 16, 2021
Extensive vaccination had resulted in reduced COVID-19 cases and mortality in certain places, such as the United States and Israel, thus giving a cautious optimism that the worst of the pandemic was over. However, this turned out not to be the case, due to unpredicted factors. One was the appearance of variants of concern, particularly the Delta variant. Another was more relaxed attitudes to viral infection and/or pandemic fatigue. Furthermore, vaccination rates stalled, particularly in the US, and an increased volume of anti-vaccination movement and misinformation on vaccines spread worldwide. All these factors have conspired to generate a new and concerning wave of COVID-19 infections, hospitalizations, and deaths.
The current COVID-19 vaccine regimens are largely protective against serious disease and death, although the duration of this protection is still unknown. The current situation of the ongoing pandemic makes it clear that the goal of vaccination is not preventing the viral infection. Certainly, the eradication of the virus is not realistic, and SARS-CoV-2 will likely continuously circulate in the population. To end this pandemic, it is urgent to vaccinate as many people as possible to minimize hospitalizations, deaths, and the emergence of new variants. We will eventually need to establish logistics for booster vaccinations based on proceeding scientific data. This will depend on information on the levels of neutralizing antibodies required for protection and other correlates of protection, duration of vaccine-induced immunity, and individuals and timing required for a booster.
- A. Puranik et al., Comparison of two highly-effective mRNA vaccines for COVID-19 during periods of Alpha and Delta variant prevalence. medRxiv, 2021.2008.2006.21261707 (2021).
- A. Sheikh et al., SARS-CoV-2 Delta VOC in Scotland: demographics, risk of hospital admission, and vaccine effectiveness. Lancet 397, 2461-2462 (2021).
- T. Tada et al., Comparison of Neutralizing Antibody Titers Elicited by mRNA and Adenoviral Vector Vaccine against SARS-CoV-2 Variants. bioRxiv, 2021.2007.2019.452771 (2021).
- J. L. Bernal et al., Effectiveness of COVID-19 vaccines against the B.1.617.2 variant. medRxiv, 2021.2005.2022.21257658 (2021).
- H. L. Moline et al., Effectiveness of COVID-19 Vaccines in Preventing Hospitalization Among Adults Aged >/=65 Years – COVID-NET, 13 States, February-April 2021. MMWR Morb Mortal Wkly Rep 70, 1088-1093 (2021).
- F. S. Vahidy et al., Real World Effectiveness of COVID-19 mRNA Vaccines against Hospitalizations and Deaths in the United States. medRxiv, 2021.2004.2021.21255873 (2021).
- C. M. Brown et al., Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings – Barnstable County, Massachusetts, July 2021. MMWR Morb Mortal Wkly Rep 70, 1059-1062 (2021).