Scientists emphasize on mask use, hand hygiene and physical distancing to curb spread of infection

The scientists have published details in a letter in the Infectious Diseases journal on August 23.

According to a systematic review in the May 2021 issue of the same journal, recurrence of SARS-CoV-2 virus infection has been reported to vary between 2.3 per cent and 21.4 per cent.

In cases of reinfection, the disease severity was found to decrease or remain unchanged in 97.3 per cent.

The authors called for studies to clarify the underlying preconditions for reinfection. The situation has become even more complicated after that mainly due to the appearance of the Omicron variant with increased transmissibility and immune escape potential.

The variant has now evolved into 283 sub lineages, including the most predominant BA.1.1, BA.2 and BA.4 and BA.5, authors Rima R. Sahay, Deepak Patil, Gajanan Sapkal, Anita Shete and Pragya Yadav have written in the letter ‘Cases of SARS-CoV-2 reinfection with Omicron BA.2 post breakthrough infection with Delta and Kappa variants’.

They identified four Covid 19 naive persons, who had taken two doses of Covishield vaccine administered at four weeks apart.

It was followed by breakthrough infection during the second wave (April 2021) and subsequent reinfection during the third wave (January 2022) in Maharashtra. The sera were obtained at first infection, pre-reinfection, after reinfection and evaluated for neutralising antibody responses against the prototype strain (B.1), Delta (B.1.617.2) and Omicron (BA.1).

The complete genome sequence revealed the infection with Kappa and Delta variants. Two cases of breakthrough infection (Kappa variant) were asymptomatic, while two cases (One Kappa and Delta variant each) were symptomatic presented with fever, sore-throat, productive cough, headache, myalgia, generalised weakness, loss of appetite, loss of smell and taste.

These four cases got reinfected with SARS-CoV-2 BA.2 sub lineage post breakthrough infection at a mean of 275 days.

Of the reinfection cases, one patient was asymptomatic, while three other patients had mild fever, cold, cough and sore-throat.

The pre-reinfection sera (collected post eight months of breakthrough) for antibodies suggested waning immune response at the pre-reinfection period.

“Even with complete doses of vaccination followed by breakthrough infection, reduced immune responses were observed at pre-reinfection. This emphasizes the need for the booster vaccination dose. Apparently, the known immune escape of Omicron and its sub lineage could also be the reason for the reinfection amongst these breakthrough cases,” the experts from the Indian Council of Medical Research – National Institute of Virology have said.

Irrespective of the immune status with vaccination or natural infections, many breakthrough and reinfections have been observed across the globe.

Considering this along with booster dose vaccination, the continuation of non-pharmaceutical interventions i.e. use of mask, hand hygiene and physical distancing would be a good strategy to curb the spread of infection, the scientists have urged.