STOCKHOLM, Dec. 9 (Xinhua) -- The influenza season is in full force in Sweden and the number of new cases has increased dramatically in a week, local media reported on Friday.
Flu cases doubled between Nov. 21 and Nov. 28, and the Public Health Agency of Sweden now classifies it as a national epidemic, Swedish daily Dagens Nyheter (DN) reported.
Most of the cases are influenza type A, of which there are two seasonal varieties: A(H1N1)pdm09, which caused the swine flu epidemic in 2009, and A(H3N2), which first emerged in 1968, DN reported.
To date, five people have been admitted to intensive care with influenza, AnnaSara Carnahan, an epidemiologist at the Public Health Agency of Sweden, told DN.
"The elderly usually cope better with H1N1. H3N2, on the other hand, affects the elderly more severely," Carnahan told DN.
She said that people are likely to be more susceptible now than in recent years because a long time has passed since the last outbreak.
Carnahan urged those belonging to risk groups -- the elderly and the vulnerable -- to get vaccinated.
The incidence of respiratory syncytial virus (RSV) infections has also increased steeply in Sweden in recent days, along with the number of COVID-19 cases and hospitalizations, DN reported.