Warnings of a spike in COVID-19 and flu from next week and coronavirus becoming a seasonal disease – 1% drop in humidity increases number of cases by 6%

Victoria’s Deputy Chief Health Officer Annaliese van Diemen has revealed authorities there are bracing for an increase in COVID-19 cases and other viruses following the relaxation of social distancing measures.

The incubation period for COVID-19 is between two and 14 days, but Dr van Diemen said that in Victoria, most people had fallen ill at the six to 10-day mark.

“But we have seen them at either end of that,” she said.

“From mid next week we might expect to see [an increase], if there was going to be an increase. We sincerely hope that is not the case and we really encourage people to get tested as soon as they get symptoms.”

The warning came as a new Australian study conducted during the early epidemic stage of COVID-19 found a link between lower humidity and an increase in the number of locally acquired positive cases – suggesting people could be at greater risk of contracting coronavirus in winter when the humidity drops.

Researchers at the University of Sydney and its partner institution Fudan University in Shanghai, China, found a 1% drop in humidity could increase the number of COVID-19 cases by 6%.

“COVID-19 is likely to be a seasonal disease that recurs in periods of lower humidity. We need to be thinking if it’s winter time, it could be COVID-19 time,” epidemiologist and lead researcher Professor Michael Ward said.

While the researchers say further study is needed of COVID-19 cases during the winter months, and outside of Sydney, the research is the first peer-reviewed study to show a relationship between climate and COVID-19 in the southern hemisphere.