Experts, however, say they are ‘rare but expected events’ when lakhs are vaccinated
The increasing number of COVID-19 reinfections following natural infections and vaccine “breakthrough” infections amongst fully vaccinated health-care workers in Kerala is emerging as a new concern even as experts reiterate that these are “rare but expected events” when lakhs are vaccinated.
They point out that immune escape variants of SARS-CoV2 can also contribute to an increase in reinfections and potentially have an adverse effect on the efficacy of vaccines, leading to breakthrough infections.
Rate of reinfections
The Indian Council of Medical Research (ICMR) puts the rate of reinfections in the country at 4.5% and that of breakthrough infections at two to four infections per 10,000. It said on Wednesday that the emergence of the virus variants and the fact that health workers are constantly exposed to the virus are the key reasons for these infections.
Post-vaccination infections have been mostly mild or asymptomatic, doctors say, because the individuals still have partial protection. In Kasaragod, all of the 12 breakthrough infections detected among health workers were asymptomatic cases, picked up through random sampling.
In Kerala, about 73% of health workers have been fully vaccinated now.
People with no symptoms transmit more than half of all cases, according to a recent model developed by the U.S. Centres for Disease Control and Prevention. This essentially means that having a grip on silent transmission from persons without symptoms is very important for controlling the pandemic.
Science still has no clear answers whether vaccinated individuals with asymptomatic breakthrough infections can still transmit the disease. Public health experts are beginning to wonder whether hospitals can become disease transmission centres if fully vaccinated staff with asymptomatic infection are unknowingly transmitting the infection.
According to the European Centre for Disease Prevention and Control, vaccines have been only evaluated for their efficacy against symptomatic cases. But none of the vaccine trials have been designed to measure reduction in transmission risk from infected vaccinated individuals.
“There is a substantial likelihood that asymptomatic breakthrough infections can result in further spread of the disease in the community. This could happen especially as people may become complacent following vaccination, and many such infections are asymptomatic. Even with a reduced viral load, a vaccinated, infected individual can still spread the disease because the virus spreads depending on the individual’s ability in generating aerosols and the physical environment it takes place in” says Rajeev Jayadevan, vice chairman, Kerala State IMA Research Cell.
Source: Read Full Article