- Jennifer Middleton, MD, MPH
As challenges with distributing COVID-19 vaccines continue, additional data is emerging regarding the two mRNA vaccines already being given in the United States (US) along with Johnson & Johnson's Janssen vaccine and the Novavax vaccine. The Janssen and Novavax vaccines are likely to soon apply for Emergency Use Authorization.
Preliminary data out of Israel suggests that the Pfizer/BioNTech vaccine is even more effective than phase 3 trials in the US suggested. The Israeli Health Ministry announced last week "that of 428,000 Israelis who had received their second doses, only 63, or 0.014 percent, had contracted the virus." It's important to note that this data hasn't yet been subject to peer review or published, though the health fund gathering the data reportedly plans to do so very soon.
Johnson & Johnson also shared preliminary data from its Janssen vaccine international phase 3 trial last week. The Janssen vaccine uses an adenovirus vector to deliver the SARS-CoV-2 spike protein. They enrolled over 43,000 participants from the US, Latin America, and South Africa and found that:
Among all participants from different geographies and including those infected with an emerging viral variant, Janssen’s COVID-19 vaccine candidate was 66% effective overall in preventing moderate to severe COVID-19, 28 days after vaccination. The onset of protection was observed as early as day 14.
Although these numbers are not as impressive as the Pfizer/BioNTech and NIH/Moderna vaccines, they still represent acceptable efficacy. Perhaps more importantly, the vaccine demonstrated "complete protection against COVID-related hospitalization and death," with none of the vaccinated participants experiencing hospitalization or death 28 days or more after vaccination. With the added bonuses of only requiring one vaccination and much simpler storage requirements (regular refrigeration), the Janssen vaccine may be an important addition to the COVID-19 pandemic arsenal.
Lastly, the Novavax vaccine (NVX-CoV2373), which works via engineered spike proteins, is showing reasonable efficacy in trials in the United Kingdom (UK). Over 15,000 participants received the 2 doses of the Novavax vaccine in the UK:
The first interim analysis is based on 62 cases, of which 56 cases of COVID-19 were observed in the placebo group versus 6 cases observed in the NVX-CoV2373 group, resulting in a point estimate of vaccine efficacy of 89.3% (95% CI: 75.2 – 95.4). Of the 62 cases, 61 were mild or moderate, and 1 was severe (in placebo group).
"The newer, more contagious variant first identified in Britain was found to have caused about 50 percent of the cases in the trial, Novavax said." Phase 2b trials in South Africa have been less impressive, with only 60% efficacy (though with a very wide 95% confidence interval of 19.9-80.1), likely due to the South Africa SARA-CoV-2 variant. Novavax is already at work on another vaccine targeting this variant. Similar to the Janssen vaccine, the Novavax vaccine can be stored in a regular refrigerator.
Assuming supply and distribution challenges are eventually overcome, vaccine hesitancy may pose another threat to decreasing SARS-CoV-2 transmission, which is critical to slowing the development of additional COVID variants. The Centers for Disease Control and Prevention (CDC) has resources and talking points to support clinicians with these conversations, and the AFP By Topic on Coronavirus Disease 2019 (COVID-19) also includes this article on "Helping Patients Make Healthy Decisions on COVID-19."