COVID-19 cases keep falling dramatically in the United States. The drop in the number of new cases per day over the past few weeks has been remarkable, and over the past three to four days new cases have decreased well below 150,000/day. We have not quite reached the new infection levels that were observed before the November surge, but the fall has been truly dramatic.
The reasons behind the continued fall in new infections is not entirely clear. People have hypothesized that new restrictions in the activity, increased mask usage, and a reduction in travel after the holidays are involved. While people have dismissed the role of vaccines, we are approaching the six week point after the rollout of the vaccine program, a timeframe that seemed to have made a difference in Israel.
Not surprisingly, deaths are falling, but not to the same degree as new cases. This is similar to what has previously been seen when changes in deaths trail changes in new cases by several weeks.
We can hope that the drops continue while vaccinations increase, and that this will control potential surges that could occur as people start traveling and increasing activities again in the spring.
Also yesterday, it was reported that South Africa had decided to stop their efforts to immunize people with the AstraZeneca COVID-19 vaccine. This decision was based on the finding that in a small segment of patients the AstraZeneca vaccine did not appear to reduce mild clinical disease from COVID-19 in South Africa. This was thought to be because the vaccine had little effect against the COVID-19 variant B.1.351 that is circulating in the country.
Of interest, the data supporting this assessment were remarkably scant. Investigators found that B.1.351 virus was poorly neutralized by blood antibodies induced by the AstraZeneca vaccine, and this neutralization activity was substantially less than with the “original” strain of the coronavirus. This was observed with both of the less protective adenovirus-based COVID-19 vaccines.
Further, in a study of 2,000 subjects in South Africa, researchers at University of the Witwatersrand stated the AZ vaccine “provides minimal protection” against mild disease caused by the new coronavirus variant circulating in South Africa. But there were only 20+ people with mild illness in the study, and the numbers were not large enough to be conclusive. No comment was made about moderate or severe disease because there wasn’t any, even in the control group!
If the data were so sparse, why did South Africa immediately stop their AstraZeneca vaccination program? In part, it is because it’s been clear that this vaccine is less effective than others, but I think more importantly, the AZ clinical trials have been conducted so poorly that it’s hard to draw a finite conclusion about its efficacy.
If the clinical trials had been conducted in a more formal and consistent manner, one could make a better argument that the vaccine would be useful despite a 20 person, non-statistically significant study. Unfortunately, AZ’s missteps now allow a tiny, non-significant study to undermine the data from almost 100,000 person trials.
In response, investigators from Oxford University, which codeveloped the vaccine with AstraZeneca, stated that they would be working on a new version of the vaccine that would be more effective against the B.1.351 virus variant. They expect to have the revised vaccine available by the fall.
I can only wish them good luck!