With Kerala reporting a large number of breakthrough COVID-19 infections in the country, questions have been asked on the efficacy of the vaccination, and why one should get the jab.
Another question, equally justifiable, being asked is on the severity of the breakthrough infection (people getting infected 14 days after they are fully inoculated), and its reasons.
After vaccination
Normally, years of efforts and experiments go into the development of a vaccine. But in the case of COVID-19, which tore across the world, the research for developing the vaccine was fast-paced. Currently, about 10 vaccines are being used worldwide against the virus, which was first reported in 2019. However, none of the vaccines are 100 per cent efficient.
Why breakthrough
The SARS-CoV-2 virus was first found at Wuhan in China in 2019. Realising the lethal potential of the virus, China conducted the genomic sequencing of the virus and provided the necessary information to researchers. The vaccines now being used were developed to counter the original virus.
The virus, however, underwent several mutations over the past two years. For instance, the Delta variant first found in India. Though studies indicated that the existing vaccines are effective against the variants, there are several unsolved issues, including the breakthrough infections.
The Kerala example
Even as the second wave declined in other States, the number of cases kept on increasing in Kerala. An expert team that studied the Kerala trend found that cases of breakthrough infection were on an uptick in districts like Pathanamthitta. The team recommended the State to be extra cautious against such cases, also to forward samples for genome sequencing.
A study later conducted by the Kerala government and the Delhi-based CISR-Institute of Genomics and Integrative Biology (IGIB) vindicated the findings of the expert team.
The Delta conundrum
A study conducted in Kerala held the Delta variant responsible for the increasing breakthrough cases in the State. The variant was responsible for the breakthrough infections in 155 cases (147 of patients had received Covishield, and eight, Covaxin). For some others, the sub-lineage of Delta caused the infection. Of the 155 breakthrough cases studied, they were infected within 16 to 124 days after receiving the vaccination. As many of 151 patients were symptomatic, but the infection was mild and no one had to be hospitalised.
Is it a cause of concern?
Experts opined that breakthrough cases were not worrying, but they should be careful not to communicate the virus to others. Vaccines considerably reduce the severity of the infection, but experts recommended all to get vaccinated so that the breakthrough infection would not be passed on to others, especially the elderly and those with comorbid conditions.
The success of Kerala
There are two answers for the high number of breakthrough cases in Kerala: One, the presence of Delta variant, and two, Kerala has been actively and expeditely vaccinating its people. Once vaccinated, all fresh cases are breakthrough infections. It should also be noted that COVID-19 has not yet peaked in Kerala unlike in other States, which have lesser new cases. However, the vaccination drive is progressing without any major glitches in the State.
A significant number of the daily fresh cases being reported now could be breakthrough infections. It has been unofficially estimated that Kerala has half of the about one lakh breakthrough infections in the country. Statistics also revealed about one lakh people in Kerala contracted the virus after getting the first dose of the vaccine.
Guarding against new variants
Though the variants are not of concern now, IGIB's genomic sequencing has found AY.1, a sub-lineage of the Delta Plus variant in Kerala. Delta, with severe spreading potential, and its variants are dominant in the State. The absence of other variants is a matter of relief for the State.
Though there is no evidence the Delta sub-lineage like AY.1 are lethal, Dr Vinod Scaria, Principal Scientist at IGIB, recommended the close monitoring of their spread. Delta and its variants are widely spread in Kerala. Dr Scaria said the immediate focus should be vaccinating senior citizens, besides continuing the COVID-19 containment measures.
