COVID-19 cases are gradually dropping in Turkey after a troubling surge over the past two months, but the danger is not over. The onset of winter gives fertile ground for the outbreak to spread. Professor Ateş Kara, a member of the Health Ministry’s Coronavirus Scientific Advisory Board, says people should be more cautious and heed measures like wearing masks, adhering to social distancing and hygiene in the winter.

"The virus used to survive only less than one minute in droplets when people cough, but it can now survive for 10 minutes," he said.

Kara told Demirören News Agency (DHA) on Wednesday that although the number of patients has decreased, people need to be warier of the virus in wintertime, noting that the virus was less active in the summer heat and sunlight. "It wasn’t able to survive, even for 30 seconds, on surfaces exposed to sunlight. Now, it increased to up to five minutes. Droplets from our mouth, if contaminated with the virus, can survive for up to 10 minutes. Therefore, we have to be far more careful about hand hygiene in particular, especially in environments outside your home. Wash your hands more with soap and water and use hand sanitizers more often," he urged the public.

Turkey has managed to pull the number of daily cases below 20,000 this week. The total number of cases since the outbreak began in the country in March has exceeded 2 million while fatalities stand above 18,000. The total number of recoveries has reached more than 1.8 million.

"The number of active cases and critical patients continues to decline. While cases are declining, infections among family members are increasing. We need to follow every precaution. Fighting this outbreak together will yield results," said Health Minister Fahrettin Koca on Twitter, shortly after the announcement of daily figures on Tuesday evening.

In order to curb the rapid rise in infection levels, the government reintroduced a slew of restrictions last month, including the closure of schools, weekday curfews and weekend lockdowns.

The government also announced a special four-day lockdown that will be implemented from 9 p.m. on Dec. 31 to 5 a.m. on Jan. 4 over the upcoming New Year's weekend to stop people from forming crowds during celebrations.

Kara said people should cancel their New Year's celebrations. "The virus’s only host is humans, and any human being you come across can be infected, even if he or she does not have any symptoms," he said.

Assessing the risk

The infection risk will persist, at least for a while, even if the mass vaccination campaign Turkey plans to carry out soon can offer protection. A group of researchers from Gazi University in the capital Ankara hopes to provide estimates on this risk and has developed a new method to measure it. The method is based on the state of ventilation in an enclosed space, the number of people in any given location, possible sources of infection and the duration of time people spend there. For instance, staying one hour in a space of 35 square meters (377 square feet) without ventilation with 30 others can lead to 14 new cases if one person among the 30 is infected, or, in terms of percentages, a 47% risk. A naturally ventilated area with the same time and crowding conditions would produce an estimated nine new cases, and a mechanically ventilated space decreases the risk to 2%.

Associate professor Zeki Yılmazoğlu, one of the researchers, told Anadolu Agency (AA) on Wednesday that the method does not give a definitive risk rate but a prediction based on variables in any environment. "Our calculation tool uses 48 quanta per hour to measure the amount of infection dose emitted to the air for measurement examples, and in medical literature, it is varied and reaches up to 300 quanta per hour, based on people’s activities, like speaking loudly or singing," he noted.

"Calculations are based on respiratory features of adults. If the infected person in an environment is a superspreader, this will change the results," Yılmazoğlu said. He also noted that the increased risk in places without ventilation highlighted the need for proper ventilation to reduce the infection risk.