Johnson & Johnson’s JNJ.N Covid-19 vaccine, called Ad26.COV2.S, has been well tolerated by subjects at two doses in clinical trials with early to mid-stage coronaviruses.
It is the only Phase 3 Covid-19 vaccine trial in the United States to test a single dose vaccine.
The researchers said that 98% of study participants for which data were available had neutralizing antibodies, which help the body fight off pathogens, one month after receiving the vaccine.
The vaccine is unique in that it is given as a single injection, rather than two doses. The reduced time needed to administer the vaccine could simply be its distribution.
Nearly 1,000 healthy adults have taken part in the clinical trial, which began after Johnson & Johnson saw that the vaccine offered strong immune protection when tested in monkeys.
The company began the last phase of the trials on Wednesday by starting a trial of 60,000 people. If the results are successful, the trial would be another step on the road to a viable vaccine against the coronavirus.
Johnson & Johnson said the trial is expected to be concluded by the end of the year or early 2021.
While the results have so far been promising, an area of concern expressed by researchers is whether or not the vaccine will be effective in older people.
There were only 15 participants included in the report who were over 65.
Participants over 65 reported side effects to the drug – such as fatigue and muscle pain – at a rate of only 36 percent. Younger participants reported these effects at a rate of 64%. Since older patients don’t experience side effects as often, researchers worry that they may not have the same immune response as younger people.
The report found that most of the side effects caused by the vaccine went away within a few days.