Phase 3 vaccine trials typically include large numbers of participants enabling them to provide efficacy estimates and good safety data. But the real test of a vaccine begins after it is implemented: how well does it work in the real world when given to millions of people?
Israel is currently in the best position to give us the answer. The country reached a deal with Pfizer (BNT162b2 mRNA vaccine) for rapid vaccine roll-out among its elderly in exchange for extensive data on real-world vaccine efficacy. The numbers are incredible:
1. Nearly all Israeli people over the age of 60 have received at least one dose of the COVID-19 vaccine already. Indeed, 80% have completed both doses of the vaccine series.
2. The age-group above 60 has shown a sharp drop in the number of confirmed COVID-19 cases. As seen in the figure below, the drop begins to occur in the middle of January when a critical number of elderly had received at least one dose of the vaccine. COVID-19 cases in other age groups are similar or show smaller drops as vaccination in these groups has not been completed.
3. The trend is even more pronounced when looking at hospitalisations for COVID-19 and severe COVID-19. Rates have plummeted in the over-60s below those of the under-60s. This is highly unusual for COVID-19, which causes most severe disease in the elderly. This trend is attributable to the high vaccination rates in this group.
4. It is notable that the main variant circulating in Israel is the so-called UK variant (B.1.1.7). This is great news as it shows that first generation COVID-19 mRNA vaccines work well against this variant. The SA variant B.1.351 and other E484K carrying variants are more prone to partially escape vaccine-induced immunity, but there is a reasonable expectation that first generation COVID-19 vaccines can still protect against severe disease from these variants.
5. Even one dose of the vaccine appears highly protective by 21 days (Hunter PR, medRxiv) of the dose. Even for those who unfortunately catch COVID-19 after a single vaccine dose, the amount of virus shed appears to be lower (Levine-Tiefenbrun M et al, medRxiv), which is great news indicating that the vaccines can reduce transmission.
The case of Israel gives us a clearer picture of a post-vaccine world where the impact of SARS-CoV-2 is mitigated to the extent that society can return to a state of normalcy.
Vaccines clearly work!
Happy Lunar New Year