After a spate of successes in the vaccines being tested in human trials, there is now a blip: a manufacturing defect in some batches of the trial vaccine being tested and marketed by AstraZeneca, which has partnered with the Oxford University vaccine group to test and market the ChAdOx1 nCOV-19 vaccine . Some volunteers, who were supposed to get two doses of vaccine a month apart, got only half the required dose in one of the injections. Intriguingly, the data suggested that the efficacy was 90% in the half/dose-full dose sub-group than the 62% in the regular full dose group. The manufacturing snafu was disclosed by neither Oxford nor AstraZeneca, but came to light after the head of the United States vaccine programme disclosed it on Twitter. The company maintains that this was not a ‘mistake’ as the manufacturing discrepancy was discovered, and disclosed to the United Kingdom regulators. It was with their approval that the batches with the reduced doses were allowed to progress. However, the company is reportedly looking at an additional trial to properly test the half-dose/full-dose regime. A reduced dosage turning out to significantly improve efficacy could mean that more vaccine can be made and distributed to the world quickly. India is among those countries that is dependent on the Oxford AstraZeneca vaccine because some of those doses will be administered to a high-priority group of 30 crore people already identified by the government.
Vaccine makers and immunologists are aware of the ‘prime boost’ technique where a limited dose of a vaccine is administered that prepares the immune system and a later shot then improves the overall production of protective antibodies. The results could even cause other vaccine manufacturers to test similar strategies. However, sober reflection leads to the ineluctable conclusion that this might not be one of the ‘lucky accidents’ of science lore. The fraction of people who got the reduced doses were under 55, and so it is not known if the dosage works for people in the older, more vulnerable group who have already been included in the high priority groups of several countries including India. Also, the number of volunteers who got the accidental dose were statistically insignificant to draw the conclusion of increased protection. Though the overall assessment, that the vaccine works, and is safe, holds, the events cloud trust in the process of scientific public communication. Companies that are otherwise jostling to prematurely announce vaccine results before scientific publication are opaque about full public disclosure. This when they have already been given a free pass in terms of accelerated regulatory processes, combining results from early trials and guaranteed government procurement. Haste and opacity will only delay the availability of a safe and efficacious vaccine as India prepares for possibly the largest immunisation programme in history.