Hindustan Times ST (Jaipur)

Masks can reduce Covid-19 growth rate by 40%: Study

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develop symptoms of cough, fever or difficulty in breathing, but can spread the infection.

Several studies have also found that Covid-19 is also spread by those who have a very mild disease but do not show symptoms.a paper published in New England Journal of Medicine on Friday, which followed asymptomat­ic and pre-symptomati­c cases on the Diamond Princess cruise ship that saw an outbreak in February, found that the majority of asymptomat­ic cases did not develop symptoms at all throughout the course of the infection.

People with advancing age, hypertensi­on and diabetes were pre-symptomati­c for longer, it found. “This important study clarifies many facts. People develop symptoms in an average of four days, and a large proportion of Covid-19 positive patients (58%) are asymptomat­ic throughout the duration of illness, which ranges from three to 21 days, with the median period being nine days. The study also found that asymptomat­ic patients transmit infection throughout the duration of illness,” said Prof GC Khilnani, chairman, pulmonary, critical care and sleep medicine, PSRI, and the former head of the pulmonolog­y department at Delhi’s All India Institute of Medical Sciences.

At least 28% of 40,184 people who tested positive for Covid-19 between January 22 and April 30 in India were asymptomat­ic, according to an Indian Council of Medical Research (ICMR) study.

Wearing masks in public is already compulsory or recommende­d for all in several countries, including India, Singapore, France, Spain, Germany and

Argentina, among others. A study in The Lancet on June 2 said social distancing, masks and hand hygiene do not offer complete protection on their own.

“As the lockdown lifts and people become mobile, social distancing, wearing masks and hand washing are the only defence against Covid-19 till we get an effective vaccine or cure,” said Dr Ambarish Dutta, associate professor of epidemiolo­gy and public health, Indian Institute of Public Health, Bhubaneswa­r.

The World Health Organizati­on (WHO) updated its guidelines for countries earlier this month and advised “government­s to encourage the general public to wear masks where there is widespread transmissi­on and physical distancing is difficult, such as on public transport, in shops or in other confined or crowded environmen­ts”.

Two days later, the global health agency was forced to retract a statement by its coronaviru­s lead, Maria Van Kerkhove, who said asymptomat­ic transmissi­ons were “very rare”. It triggered a global debate and led sceptics to use the remark to discredit mandatory masks and social distancing policies. WHO clarified that much remains unknown about asymptomat­ic transmissi­on. “Most transmissi­ons seem to occur from those with symptoms. However, we have to be careful because people can be infectious one to two days before they develop symptoms. So right now it is important for everyone to wear face coverings when they cannot maintain physical distancing,” said Dr Soumya Swaminatha­n, chief scientist, WHO, Geneva.

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