Is it worth getting a Covid-19 antibody test?

There is no value in getting an antibody test, says Dr Marlin McKay.

McKay, who runs his own medical practice in Roodepoort, told TimesLIVE the test has no value in terms of diagnosis because it doesn’t determine when or where someone contacted Covid-19.

“It won’t tell you whether your antibodies will finish in the next week or month so it’s a bit of a waste,” he said.

“It can also give you a false sense of security, making you feel like you don’t have to stick to wearing a mask.”

McKay said antibody tests should not be used for diagnosis or to give people a sense of protection.

A new study carried out in collaboration with Oxford University found a longer gap between doses of the Pfizer vaccine leads to higher overall antibody levels.

The study was conducted to help inform vaccination strategies against the Delta variant, which reduces the effectiveness of the first dose of Covid-19 vaccine even though two doses are still protective.

“For the longer dosing interval, neutralising antibody levels against the Delta variant were poorly induced after a single dose, and not maintained during the interval before the second dose,” the study authors said.

“After two vaccine doses, neutralising antibody levels were twice as high after the longer dosing interval compared with the shorter dosing interval.”

Neutralising antibodies are thought to play an important role in immunity against the coronavirus but not the entire picture, with T cells also playing a part.

The study found overall T cell levels were 1.6 times lower with a long gap compared with the short dosing schedule of three to four weeks, but a higher proportion were “helper” T cells, which support long-term immune memory, with the long gap.