Cases of the flu now ‘high’ in four Massachusetts regions: Why are they rising at a time they are usually falling?

While cases of COVID-19 have continued to increase this spring after hitting a low in the beginning of March, it’s not the only virus out there making a comeback.

If you or someone you know is sick and testing negative for COVID, you may have the flu.

Cases of influenza across Massachusetts have been on the rise for the past two months. According to the weekly flu report from the Massachusetts Department of Public Health, the estimated weekly severity of the flu across the state is now at “moderate” levels. Yet a closer look shows that Central, Northeast, Southeast and West regions have now grown to “high” severity levels.

According to DPH, weekly severity is determined by combining influenza-like illness, hospitalizations, and influenza-positive test results reported to the state.

But what’s more unusual is that the levels have been climbing at a time of year they are typically in decline.

The weekly flu report from the state tracks influenza-like illnesses as reported by 93 “sentinel sites” across the state. Reports from the sites are used throughout the season to help track influenza activity in individuals who are not tested. Trends in influenza-like illnesses have been shown to mirror influenza trends, the state reports.

“The majority of patients with influenza-like illness are not tested; therefore, the number of positive test results does not reflect the total number of influenza cases in Massachusetts,” the state said in its weekly report.

Yet, confirmed lab tests also show cases have climbed.

Laboratory confirmed flu cases increased by 27% this week, according to DPH.

According to the Centers for Diseasce Control, flu activity is highest right now in the Northeast, South-Central and Mountain regions of the US

Influenza in Massachusetts

The percentage of visits to sentinel provider sites in Massachusetts for influenza cases for the past four years (Massachusetts Department of Public Health).

Influenza was largely dormant in 2020 and 2021, which health experts attribute to shutdowns, masking, social distancing and other measures that accompanied the coronavirus pandemic, which not only worked to curtail COVID but had the effect of stopping the spread of other communicable diseases as well .

Flu cases this year are back, somewhat. According to data from the state, reports of influenza-like cases from provider sites this year are higher than the 2020-2021 season but still much lower than the two seasons prior to the pandemic.

They also began rising about the same time that COVID cases began to uptick as well — around the beginning of March.

Although officials have not identified any clear reason for flu cases rising in April — a time they have typically declined — a return to normal following pandemic restrictions is one possible cause.

“Most of us have thought that this last end-of-season smoldering, slightly increasing number of cases here and there is probably due to people taking off their masks, going out to group activities, going indoors to restaurants, worship services, concerts, starting to go back in-person in business — all of those kinds of activities are still presenting some opportunities for this respiratory virus to be spread,” Dr. William Schaffner, the medical director of the National Foundation for Infectious Diseases, told Healthline.

Influenza in Massachusetts

The number of laboratory confirmed influenza cases in Massachusetts by week (Massachusetts Department of Public Health).

The flu vaccination rate for all ages in Massachusetts is currently 48%, the Department of Public Health reports. By comparison, more than 75% of the state is fully vaccinated against COVID. Influenza A (H3N2) is the predominant strain in Massachusetts right now, which the vaccine protects against. However, vaccine effectiveness can wane over time as viruses continue to evolve.

As of Feb. 12, 2022, the CDC had genetically characterized 65 influenza A viruses from US Influenza Vaccine Effectiveness Network participants.

The percent of hospitalizations associated with influenza in Massachusetts is 0.89%, according to DPH, which is higher than last season and the 2019-2020 season, but lower than the 2018-2019 season.

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