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Covid-19: J&J, Pfizer jabs effective on variants despite diminished antibodies

Washington - Levels of antibodies against variants first identified in the UK, South Africa, Brazil and California were about three-fold lower

The one-dose Johnson & Johnson Covid-19 vaccine and the two-dose vaccine from Pfizer and BioNTech appear to protect against worrisome coronavirus variants despite diminished levels of antibodies that can neutralize the newer versions of the virus, two studies in the journal Nature suggest.

The authors of both studies said other immune responses may be compensating. In one study, published on Wednesday, researchers experimented with blood from people who had received the J&J vaccine two months earlier.

Compared to their levels of neutralizing antibodies against the virus that was circulating early in the pandemic, levels of neutralizing antibodies against variants first identified in the UK, South Africa, Brazil and California were about three-fold lower. However, the researchers observed other “robust” immune activity and cells whose responses against the variants were undiminished.

In clinical trials, the researchers noted, the J&J vaccine protected against symptomatic Covid-19 in South Africa and in Brazil, where most cases were caused by the variants. Its effectiveness in these regions raises the possibility that these other immune responses may be contributing to protection, co-author Dr. Dan Barouch of Beth Israel-Deaconess Medical Center in Boston, said in a statement.

In a separate study using blood from recipients of the Pfizer/BioNTech shots, levels of antibodies that could neutralize concerning variants first identified in India and Nigeria were lower compared to an earlier version of the virus, researchers reported on Thursday.

Still, they reported “robust neutralization” of all tested variants. Neutralizing antibodies, the researchers said, do not reflect all potentially protective vaccine responses.