From what I've read and seen on the news, the current crop of vaccines in development have a pretty high rate of developing antibodies on the first dose. I think @TLS Guy may have already posted this, but at least the Oxford version has 100% antibody after the second dose. I'll let him or @Swerd correct me on that if I'm misremembering.That trial of the Oxford\/Astra Zeneca vaccine tested 1077 people. About half of the people (543) received the experimental corona virus vaccine and half (534) got the meningitis vaccine, as a control vaccination. This trial has not gone on long enough to test for how effective the vaccine is at preventing COVID-19 disease, and those numbers of people are too small to provide statistically significant values for effectiveness. Larger trials of that vaccine will be done, with about 30,000 people, to test efficacy.\n\nhttps:\/\/www.thelancet.com\/journals\/lancet\/article\/PIIS0140-6736(20)31604-4\/fulltext\n\nOf the 543 corona virus vaccine recipients, 10 people also got a second dose of the vaccine. The data on their responses will be of interest, if neutralizing antibody responses are also shown to be protective in humans. This is not known at present.\n\nImportantly, there are accumulating data that suggest T-cell responses play an important role in COVID-19 immune responses. Individuals who had been exposed to the virus, but never developed disease symptoms, did develop a robust memory T-cell response, in the absence of a measurable antibody response.\n\nSo, don't attach too much importance – yet – to that report of the 10 people who received two doses. It was done in only 10 people, and it showed greater antibody response. But the T-cell responses were already robust after a single dose. A second dose did not add to that.