Data from the Department of Health and Mental Hygiene shows a spike in flu and RSV cases citywide.

In the last data collection period released on Dec. 21, there were nearly 5,000 cases of RSV and just under 8,000 cases of the flu.

Dr. Edward Chapnick, chief infection prevention officer at Maimonides Hospital, told News 12 that their hospital has seen an increase of patients coming in with severe symptoms.

"The numbers are increasing significantly. Our emergency room and our hospital are pretty much full on a constant basis," he said.

Chapnick says the official numbers put out by the Health Department are likely an undercounting of the true number of cases.

"Many people have mild cases. They resolved at home and they never report it so the true number is almost definitely higher," he said.

He told News 12 that while masking in public places is a good idea for those who are immunocompromised or know that they are infected, vaccinations are key for helping drop the numbers of cases and protection vulnerable populations. He said less than half of those eligible to get a flu vaccine have chosen to do so.

While everyone is at risk of the flu and can get vaccinated, the risk is mainly to younger children and the elderly when it comes to RSV. Vaccines are only available to those ages 75 and older or 60+ with a qualifying health condition.

"It’s important to be vaccinated to help increase protection," he said.