There was more news on COVID-19 vaccines this week with two more companies - Novavax and Johnson & Johnson - releasing their phase III efficacy data. Novavax manufactures a subunit vaccine (essentially the 'spike' protein of SARS-CoV-2) while J&J's is an adenovirus-vector vaccine given as a single dose.
In the table below, I summarize the efficacy data (primary outcome measures) of all vaccine candidates that have released phase 3 trial results so far.
The good news:
1. All vaccines exceed the minimal WHO-mandated vaccine efficacy limit of 50%. This means that a person who receives a COVID-19 vaccine is much less to fall ill from COVID-19 than a person who does not.
2. Vaccines do very well for protection against severe disease. Most vaccine trials had no severe COVID-19 cases in the vaccine arms. Even the J&J vaccine was able to reduce risk of severe disease after just one dose. This is really important to protect elderly and relieve pressures on healthcare systems.
3. Most of these vaccines are stable at refrigerator temperatures. We now have plenty of good candidates for a truly global rapid vaccine rollout. The more successful candidates, the better.
4. Excitingly, real-world data from Israel shows that people start showing protection against COVID-19 as soon as 2 - 3 weeks after the first dose of a mRNA vaccine (Chodcik G et al, medRxiv, 2021).
The not-so-good news:
Some SARS-CoV-2 variants do make a difference to vaccine efficacy. Luckily, the B.1.1.7 (UK) variant does not seem to affect vaccine efficacy a lot. This is based on phase III RCTs of the Novavax and J&J vaccines in the UK as well as testing the neutralizing power of vaccine sera (mRNA and inactivated) against the variant virus (Sapkal GN et al, bioRxiv, 2021; Rathnasinghe R et al, medRxiv, 2021).
However, the B.1.351 (South Africa) variant probably does reduce vaccine efficacy. This was observed in both the Novavax and J&J trials where the US/UK parts of the trials showed higher efficacy than the South African trials. Luckily, even against B.1.351, these two vaccines show an efficacy >= 60%. So, there is still decent protection! Constantly monitoring for emerging variants, containing their spread and checking vaccine efficacy against them is going to be a recurring theme in the coming months.
In summary, it is a truly incredible achievement to have these many efficient vaccines within a year of the pandemic. Although vaccines face some challenges from emerging variants, there is no doubt that they are our best hope out of the pandemic!
Have a good weekend.
(First published at author's Facebook)