What vaccines are available in other countries or on the horizon for the U.S.?
This two-dose vaccine is a weakened adenovirus-based vaccine. Researchers genetically altered a weakened version of a common cold virus (adenovirus) that causes infections in chimpanzees so it carried a gene for the COVID-19 spike protein; this will train a person’s immune system to recognize the real coronavirus.
This vaccine has been approved for emergency use in the United Kingdom, the European Union, and Canada.
One dosing regimen showed vaccine efficacy of 90% when AZD1222 was given as a half dose, followed by a full dose at least one month apart, and another dosing regimen (n=8,895) showed 62% efficacy when given as two full doses at least one month apart. The combined analysis from both dosing regimens (n=11,636) resulted in an average efficacy of 70%
No hospitalizations or severe cases of the disease were reported in participants receiving the vaccine.
This vaccine was found to have similar efficacy for the U.K. variant than the original strain; however, in South Africa, it was found to have low efficacy for mild to moderate COVID-19, causing concerns that it is not effective against that variant; because the study was small and had young and healthy participants, it could not assess for efficacy against moderate to severe COVID-19
New data (currently waiting for peer review) shows that that the effect of dosing interval on efficacy is pronounced, with vaccine efficacy rising from 54.9% with an interval of less than six weeks to 82.4% when spaced 12 or more weeks apart
New data also shows that a single standard dose of the vaccine is 76% effective at protecting from primary symptomatic COVID-19 for the first 90 days post vaccination, once the immune system has built this protection 22 days after the vaccination.
This two-dose vaccine is made from a stabilized form of the coronavirus spike protein using the company’s recombinant protein nanoparticle technology. The purified protein antigens in the vaccine cannot replicate and cannot cause COVID-19. The vaccine also contains a proprietary adjuvant, MatrixMTM. Adjuvants are additives that enhance desired immune system responses to vaccine.
Clinical trials in the U.K and South Africa have reported data; The US and Mexico PREVENT-19 Phase 3 clinical trial has randomized over 16,000 participants toward our enrollment goal of 30,000.
89.3% efficacy in Phase 3 UK trial with over 50% of cases attributable to the now-predominant UK variant and the remainder attributable to COVID-19 virus
49.4% efficacy in total study population (60% efficacy in 94% of the study population that was HIV negative) was demonstrated in Phase 2b South Africa trial with over 90% of sequenced cases attributable to prevalent South Africa escape variant.