RIGA, Dec. 8 (Xinhua) -- Latvia's Center for Disease Prevention and Control (CDC) on Monday informed of the start of the annual influenza epidemic in the country and encouraged vaccination as the most effective protection.

The CDC declared the start of the flu epidemic as of Tuesday, Dec. 9, based on monitoring data from the National Microbiology Reference Laboratory (NMRL).

According to the CDC, from Dec. 1 to 7, the share of positive flu tests at the NMRL rose sharply to 18.1 percent, up from 9.1 percent a week earlier. This exceeds the epidemic threshold by 10 percent.

The CDC stated that it is continuing to compile other flu monitoring data for this period, which will be published in its weekly report.

Experts stress that the groups most vulnerable to severe flu include seniors and people with chronic diseases such as cardiovascular, lung, and kidney diseases, diabetes, cancer, chronic infections, and those with weakened immune systems. The flu also poses heightened risks to young children and pregnant women.

According to experts, vaccination remains the best protection against influenza and its complications. Given that immunity builds up within ten to 14 days after vaccination and the flu circulation typically continues until late May, health authorities emphasize that it is not too late to get vaccinated even after an epidemic has begun. Enditem