A modelling study has revealed that prohibition on public gatherings can reduce the Covid-19 reproduction number (R) — a key measure of virus spread — by 24 per cent within a month.

The study, published in the journal Lancet , looked at the data from 131 countries that suggested individual protocols, including stay at home orders and internal movement limits, are proportional to the reduction in the spread of the virus.

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However, combined measures are more effective at reducing transmission, the researchers said.

One of the authors, Professor Harish Nair from the University of Edinburgh, UK, said: "We found that combining different measures showed the greatest effect on reducing the transmission of Covid-19. As we experience a resurgence of the virus, policymakers will need to consider combinations of measures to reduce the R number."

"Our study can inform decisions on which measures to introduce or lift, and when to expect to see their effects, but this will also depend on the local context — the R number at any given time, the local healthcare capacity, and the social and economic impact of measures," Nair said.

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The researchers believe that such prohibition can significantly bring down the level of the viral load as it will reduce the event of super spreaders.

When looking at the measures individually, a ban on public events was associated with the greatest reduction in R — 24 per cent reduction after 28 days, the researchers noted.

Re-opening of schools

According to the researchers, the measures most strongly associated with an increase in R were lifting bans on gatherings of more than 10 people and re-opening of schools.

"We found an increase in R after reopening schools but is not clear whether the increase is attributable to specific age groups, where there may be substantial differences in adherence to social distancing measures within and outside classrooms," Nair added.

"Furthermore, more data are needed to understand the specific role of schools in increased SARS-CoV-2 transmission through robust contact tracing," he said.

However, the study did not incorporate other pivotal factors that have an impact on R, including compliance with the interventions, changes in population behaviour, sub-national differences in R, or the effects of contact tracing and isolation — all of which vary by context.

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