Patients who have recovered from Covid-19 can again get infected once the antibodies of the viral disease starts depleting, the Indian Council of Medical Research (ICMR) said on Tuesday.
“According to the Centre for Disease Control (USA), you call it a reinfection (of Covid-19) if the person is reinfected after 90 days from turning negative to the Sars-CoV-2 after testing positive to it. However, there are multiple studies which suggest that the antibodies that develop after Covid-19 sustain for up to five months,” said Balram Bhargava, Director-General of ICMR, while answering a query in the weekly press briefing of the Union Health Ministry.
“Since the disease is new, we do not have any further information about it. However, people can recontract the infection if antibodies start depleting from the body,” he added.
Bhargava also stressed that one should not become complacent, and follow all precautionary measures such as wearing mask, staying cautious and not relying on antibodies to astray the re-contraction.
“Even after contracting the virus, one must not avoid using a mask,” he cautioned.
Bhargava also informed that the ICMR is conducting an assessment on the subject of reinfection as commissioned by the Union Health Ministry, and its result will be out shortly.
Union Health Minister Harsh Vardhan had earlier informed that the ICMR had set up a committee of experts to study reported cases of reinfection among Covid-19 patients. However, he had termed some of the supposed cases of Covid reinfections that had been reported as “misclassified”.
As per the ICMR, so far, three cases of reinfection have been reported in the country — two from Mumbai and one from Ahmedabad. The apex body of medical research had also stated that the cut-off date for depletion of antibodies set by it for the assessment is 100 days from the infection.
“There are various cut-off days that are being referred to for reinfection. Though the public is going by up to 110 days, we are taking 100 days as the cut-off period because the antibodies last until then,” Bhargava had said.
Daily mouthwash may inactivate human coronaviruses
Meanwhile, scientists have found that certain oral antiseptics and mouthwashes may have the ability to inactivate human coronaviruses. The results, published in the Journal of Medical Virology, indicate that some of these products might be useful for reducing the amount of virus in the mouth after infection and may help to reduce the spread of SARS-CoV-2, the coronavirus that causes Covid-19.
“While we wait for a vaccine to be developed, methods to reduce transmission are needed. The products we tested are readily available and often already a part of people’s daily routines,” said study researcher Craig Meyers from the Penn State University in the US.
During the study, the research team tested several oral and nasopharyngeal rinses in a laboratory setting for their ability to inactivate human coronaviruses, which are similar in structure to SARS-CoV-2.
The products evaluated include a one per cent solution of baby shampoo, peroxide sore-mouth cleansers, and mouthwashes.
The researchers found that several of the nasal and oral rinses had a strong ability to neutralize human coronavirus, which suggests that these products may have the potential to reduce the amount of virus spread by people who are Covid-19-positive.
They used a test to replicate the interaction of the virus in the nasal and oral cavities with the rinses and mouthwashes.
They treated solutions containing a strain of human coronavirus, which served as a readily available and genetically similar alternative for SARS-CoV-2, with the baby shampoo solutions, various peroxide antiseptic rinses and various brands of mouthwash.
They allowed the solutions to interact with the virus for 30 seconds, one minute and two minutes, before diluting the solutions to prevent further virus inactivation.
According to Meyers, the outer envelopes of the human coronavirus tested and SARS-CoV-2 are genetically similar so the research team hypothesizes that a similar amount of SARS-CoV-2 may be inactivated upon exposure to the solution.
To measure how much virus was inactivated, the researchers placed the diluted solutions in contact with cultured human cells.
They counted how many cells remained alive after a few days of exposure to the viral solution and used that number to calculate the amount of human coronavirus that was inactivated as a result of exposure to the mouthwash or oral rinse that was tested.
The one per cent baby shampoo solution, which is often used by head and neck doctors to rinse the sinuses, inactivated greater than 99.9 per cent of human coronavirus after a two-minute contact time.
Several of the mouthwash and gargle products also were effective at inactivating the infectious virus.
Many inactivated greater than 99.9 per cent of the virus after only 30 seconds of contact time and some inactivated 99.99 per cent of the virus after 30 seconds.
The results with mouthwashes are promising and add to the findings of a study showing that certain types of oral rinses could inactivate SARS-CoV-2 in similar experimental conditions, the study noted.
With IANS inputs