What vaccines are available in other countries or on the horizon for the U.S.?

Moderna

• In mid-March, a phase 1 study started for Moderna’s is next-generation mRNA (mRNA-1283) vaccine that is refrigerator-stable and thus could be easier to distribute and administer.

AstraZeneca-Oxford Vaccine

• Background
  • 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.
• Efficacy
  • 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
  • Data 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
  • 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.

Recent News for AstraZeneca

Recent News for AstraZeneca

The Data Controversy

On Monday, March 22, AstraZeneca shared in news releases that its 32,449-person clinical trials in the United States, Chile and Peru showed the vaccine was 79% effective in protecting participants from symptomatic COVID-19, and that it was 100% effective against hospitalization or death.

On Tuesday, March 23, the Data and Safety Monitoring Board (independent experts) expressed concerns with the news release because more recent data showed an efficacy ranging from 69%-74%. AstraZeneca released results on March 25 which state that the vaccine is 76% effective at preventing symptomatic COVID-19, 100% efficacy against severe disease and hospitalization, and 85% efficacy in preventing symptomatic COVID-19 in participants age 65 years and older.

Blood Clots

The European Medicine Agency (EMA) concluded on April 7^th that that unusual blood clots with low blood platelets should be listed as very rare side effects of the AstraZeneca vaccine.

The EMA wanted health care providers and people receiving the vaccine to remain aware of the possibility of very rare cases of blood clots combined with low levels of blood platelets occurring within two weeks of vaccination. So far, most of the cases reported have occurred in women under 60 years of age within weeks of vaccination. Based on the currently available evidence, specific risk factors have not been confirmed.

The Pharmacovigilance Risk Assessment Committee (PRAC) noted that the blood clots occurred in veins in the brain (cerebral venous sinus thrombosis, CVST) and the abdomen (splanchnic vein thrombosis) and in arteries, together with low levels of blood platelets and sometimes bleeding.

The Committee carried out an in-depth review of 62 cases of cerebral venous sinus thrombosis and 24 cases of splanchnic vein thrombosis reported in the EU drug safety database (EudraVigilance) as of March 22, 2024, 18 of which were fatal. The cases came mainly from spontaneous reporting systems of the EEA and the UK, where around 25 million people had received the vaccine.

According to the EMA, the reported combination of blood clots and low blood platelets is very rare, and the overall benefits of the vaccine in preventing COVID-19 outweigh the risks of side effects.

Novavax vaccine

• Background
  • 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.
• Efficacy
  • 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.

Sources

• CDC
• Vaccine Comparison
• AstraZeneca-Oxford
• AstraZeneca-Oxford Efficacy
• AstraZeneca-Oxford UK
• AstraZeneca-Oxford EU
• AstraZeneca-Oxford South Africa
• AstraZeneca-Oxford New Data
• AstraZeneca Canada
• Novavax Efficacy
• European Medicine Authority
• AstraZeneca Safety
• EMA AstraZeneca and Blood Clots
• Moderna Next Generation Vaccine 

  Updated: April 7, 2024