THIRUVANANTHAPURAM: For several months, minimising exposure was considered an unavoidable part of the Covid prevention strategy, in the hope that an improvement in vaccination coverage would reduce the risk of infection. The lockdown too was implemented in accordance with that strategy, at the cost of economy. It has worked well, except for the fact that the virus has started infecting people irrespective of their vaccination status.
People are now increasingly exposed to the pathogen with the easing of restrictions. As a result, the infection is catching up with people who were not infected earlier. The number of breakthrough infections -- when fully vaccinated persons get infected 15 days after the second dose -- has also increased. At the current rate, one in four people contracting the virus is a breakthrough infection. And it is likely to become one in three persons soon.
So far, over 48 lakh people have tested positive in the state. Even when the sero-prevalence survey found that over 82% of the adult population have antibodies against Covid, the test positivity remains high, at around 10%. Health experts are of the view that only the immunity received from natural infection would last longer, and eventually lead to herd immunity. “People who were infected with the Wuhan-variant of Covid and those who gained immunity only through vaccination have chances of getting infected with the Delta variant. However, if they do contract the infection, it will be milder in most cases,” said Dr N M Arun, internal medicine specialist and public health activist.
Reinfections — when persons who have recovered gets infected again — and breakthrough infections have become noticeable with the spread of the Delta variant in May, said health department’s N C Krishnaprasad, who has been closely following the Covid data. The breakthrough-infection level is nearing 30% when the state has given a double dose of vaccine to over 44% of the eligible population. According to health experts, the proportion of breakthrough infections is likely to go up with the vaccination coverage.
“When the entire population becomes fully vaccinated, all the new positive cases and the deaths will be in the breakthrough category, though it will be less in numbers,” said Dr Arun. “The vaccination strategy should have focused on vaccinating those above 80, and then those with comorbidities. People with compromised immunity will be safe only when those around them have natural immunity. Those who gain immunity through vaccination can still get breakthrough infection and can be carriers of the infection,” he added.
Dr Padmanabha Shenoy, an immunologist who recently published international studies on the infection-neutralising capacities of various vaccines, said more vaccinated people are likely to get the infection in the days to come. The reopening of schools in November is likely to be a major event that would spread infection, experts pointed out.
Analysis of new and breakthrough cases
Even when sero-prevalence survey found that over 82% of adult population have antibodies against Covid, the TPR remains high, at around 10%. A look at Covid figures