Johnson & Johnson COVID-19 vaccine may be ineffective in elderly

There are a number of COVID-19 vaccine candidates being tested across the globe, and Johnson & Johnson’s candidate has produced a strong immune response in test subjects. Called Ad26.COV2.S, the vaccine was well-tolerated by test subjects during two dosage instances in its early to mid-stage clinical trial.

According to researchers, 98% of the participants in the study developed neutralising antibodies one month after receiving the vaccine.

While results have been promising thus far, researchers are concerned that the vaccine will be ineffective in the elderly. Participants over 65 years old reported adverse reactions to the drug – like fatigue and muscle aches – at a rate of 36%. Younger participants reported those effects at a rate of 64%. Since the older patients weren’t experiencing side effects as often, researchers worry they may not have the same immune response as younger individuals.

What makes this vaccine unique is that it is delivered in a single shot instead of two, as is typical of other vaccines. This is done to reduce the time needed to deliver the vaccine and simplify distribution.

Nearly 1000 participants partook in the clinical trial, after Johnson & Johnson saw that the vaccine provided strong immune protection when tested on monkeys. It is currently the only Phase 3 COVID-19 vaccine trial being tested in a single dose vaccine in the United States.