https://www.latimes.com/science/story/2021-01-29/as-coronavirus-variants-threaten-immunity-the-race-to-vaccinate-shows-pitfalls
…The U.S. company Novavax reported this week that although its vaccine was nearly 90% effective in clinical trials conducted in Britain, the figure fell to 49% in South Africa — and that nearly all the infections the company analyzed in South Africa involved the B.1.351 variant that emerged there late last year and has spread to the United States and at least 30 other countries.
Johnson & Johnson announced Friday that its new shot was 72% effective against preventing moderate or severe illness in the United States, compared with 66% in Latin America and 57% in South Africa.
https://www.cdc.gov/flu/vaccines-work/vaccineeffect.htm#studies
…CDC conducts studies each year to determine how well the influenza (flu) vaccine protects against flu illness. While vaccine effectiveness (VE) can vary, recent studies show that flu vaccination reduces the risk of flu illness by between 40% and 60% among the overall population during seasons when most circulating flu viruses are well-matched to the flu vaccine. In general, current flu vaccines tend to work better against influenza B and influenza A(H1N1) viruses and offer lower protection against influenza A(H3N2) viruses.
