Efficacy and Safety of COVID-19 Vaccines in Older People

Roy L. Soiza; Chiara Scicluna; Emma C. Thomson


Age Ageing. 2021;50(2):279-283. 

In This Article

Live-attenuated and Inactivated Virus Vaccines

Traditional vaccines have often involved live-attenuated or inactivated organisms. The principal advantage of such a vaccine is that the similarity to the natural infection may make a stronger and lon-lasting immune response more likely. No one knows how long immunity lasts after infection with SARS-CoV-2, although the very few cases of confirmed re-infection since the start of the pandemic suggests a high level of immunity is conferred for a minimum of 1 year and possibly much longer. However, live vaccines may be risky in those with immunosuppression and frail immune systems, potentially including those at highest risk of COVID-19 such as older people with frailty. Consequently, there are few live-attenuated vaccines in development. A safer alternative may be to develop inactivated viruses, even though these generally confer less long-acting immunity and typically require regular boosters.[6,10] Valneva has developed an inactivated SARS-CoV-2 virus that is ready for testing in Phase I/II trials prior to commencing Phase III in early 2021. China has also developed two inactivated virus vaccines showing promising antibody responses and low adverse events, with both lower in older age groups but only up to the age of 59. No data are yet available from Phase III studies or their Phase I/II study in people aged over 60.