With input from Dr Monica Vasudev

1340: Medpage Today Excerpts:  Vaccines less effective against South Africa variant

Good News and Bad News for Novavax COVID-19 vaccine as data from Britain are encouraging, but those from South Africa raise questions

1. Novavax makes use of nanoparticle technology and an adjuvant with recombinant protein. The vaccine can be stored at 2º to 8º C and can be transported in a ready-to-use liquid formulation.
2. This is a recombinant coronavirus spike protein, produced in insect cells. It represents a relatively traditional technology, and differs from the COVID-19 vaccines being distributed at present.
3. This vaccine candidate exhibited close to 90% efficacy against COVID-19 in a cohort with half the cases caused by the new UK variant. However, in the South Africa trial, the overall vaccine efficacy was found to be less than 50% against cases largely caused by the South African variant.
4. The study also demonstrated that previous infection with the wild-type strain may not completely protect against new infection from the variant.
5. UK ARM: An interim analysis of a phase III trial done in Great Britain noted 89.3% efficacy against PCR-confirmed symptomatic COVID-19. The results were based on 62 COVID-19 cases among around 15,000 participants; 56 cases were noted in the placebo group and 6 in those receiving the vaccine. Of the 62 cases, only one was severe.
6. According to a preliminary analysis, 32 of the 62 cases were from the UK variant.
7. Based on PCR testing, vaccine efficacy was reported to be 95.6% against the original strain while it was 85.6% against the UK variant strain in the post-hoc analysis.
8. The phase III study recruited adults 18-84 years of age (27% >65 years of age). The primary endpoint was PCR-confirmed symptomatic COVID-19 at least 7 days after the second of the two-dose regimen in serologically negative subjects.
9. Adverse events were infrequent and mostly comparable between the groups.
10. South Africa Arm: Phase IIb trial was conducted in South Africa which included nearly 6% of HIV-positive participants. There was 60% efficacy in the HIV-negative participants. The efficacy lesser in the HIV-positive participants. There was an overall vaccine efficacy of 49.4% for the entire study population.
11. 29 COVID-19 cases were reported in the placebo group (one severe) and 15 in the vaccine group (none severe). Most 25/27 involved South African variant.
12. The trial included more than 4,400 patients starting in August, with data from September through mid-January.
13. Nearly one-third third of patients recruited were seropositive for COVID-19 infection at baseline. Depending on when the trial started, pre-trial infections were considered to be due to the original strain, while infections occurring during the trial were considered to be caused by variant strain.
14. The data suggest that previous infection with COVID-19 may not provide complete protection against subsequent infection by the South Africa variant.
15. A booster dose and/or combination bivalent vaccine for the new strains is being looked into. Plans are also being made to test these new vaccines in the second quarter of 2021.

 Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA