'Unjabbed, Infected People Have Low Antibody Levels'

Researchers from the University of Hong Kong and the Chinese University said on Monday their study of vaccine responses showed that people vaccinated against Covid-19 developed a “more robust” antibody response against variants of the virus after catching Omicron than those who are unvaccinated.

After comparing the antibody responses in a mix of vaccinated and unvaccinated people, they found that an Omicron infection in an unvaccinated person induced only a weak antibody response which also reacted weakly to other coronavirus variants.

In contrast, researchers found that those who were vaccinated developed high antibody responses after getting infected with Omicron. Such antibody responses also reacted strongly against a range of coronavirus variants including Beta and Delta, they said.

‘Vaccination can help do more, other than preventing severe Covid-19 outcomes. Those who had been fully vaccinated with either the BioNTech or Sinovac vaccines and then got breakthrough infection have very strong and very broad immunity against many variants including BA.2, BA.1 and others,” said lead researcher, Professor Malik Peiris from the University of Hong Kong’s School of Public Health.

Another lead researcher, Professor David Hui from the Chinese University, said it is important for unvaccinated people to get jabbed even if they were previously infected with Omicron.

"Do not assume an Omicron infection in unvaccinated individuals alone can induce strong immunity to protect yourself against future variants. Antibody response induced by a natural infection with Omicron in unvaccinated people is weak and not broadly reactive to other variants of concern. These patients are highly recommended to get vaccinated after full recovery from infection,” Hui said.

The findings of the study have been published on the medical journal, Eurosurvillence.