2016-2017 Flu Season Losing Momentum but Far from Over

In a sign that the flu season is possibly slowing in the United States, the Centers for Disease Control and Prevention (CDC) has recently reported a slight decrease in influenza activity, though the virus is still widespread in most of the country and the elderly have been hard hit this season.

In the week ending February 18, the CDC’s weekly FluView report noted that the proportion of people seeing their health care provider for influenza-like illness was 4.8%, down from the previous week’s rate of 5.2%. At the same time, flu activity is now widespread in 44 states after hitting a high of widespread activity in 46 states the prior week. While flu activity remains elevated over the baseline rate of 2.2% for influenza-like illness, the new national report offers some good news during a flu season marked by severe illness.

On average, flu season has typically lasted 13 weeks for the past 15 seasons, though it can last for as many as 20 weeks. While flu activity peaks between December and March, it can continue into May, and so health officials are reminding the public that it’s not time to let down their guard against the flu. This season, which was dominated by the influenza A H3N2 strain of the flu virus, has seen more severe illness, particularly for those 65 years of age and older. The recent CDC report noted that the flu hospitalization rate for US senior citizens is 155.2 per 100,000, higher than for any other age group. The rate for those ages 50 to 64 years is 32.8 per 100,000, while children under 5 years are currently hospitalized for the flu at a rate of 20.8 per 100,000.

In Massachusetts, health officials recently reported that flu activity was hitting its peak in the state earlier than the 2015-2016 season, but later and with few hospitalizations than the state saw in the 2014-2015 season. The dominant H3N2 influenza strain has led to more severe illness and more hospitalizations there among those 65 and older, much as it has in other states.

Despite the recent unseasonably warm weather in Maryland and other states, flu activity levels have remained high and widespread in the state with 52% of all influenza-related hospitalizations occurring in those age 65 and older. Several Baltimore-area hospitals in the state have put into place restrictions on visitors, including children and individuals with flu symptoms who may infect patients.

During a season where the flu vaccine has been found to be 48% effective at preventing illness, a recent study published in The British Medical Journal has suggested that supplementation with vitamin D may help reduce the risk of acute respiratory infections, such as those that may occur with the flu, pneumonia, or the common cold. While the study authors note that the supplement does not prevent disease, they noted a 12% reduction in the proportion of participants experiencing at least one acute respiratory tract infection among those taking vitamin D. Their findings do not suggest that supplements may replace the protective benefits of the flu vaccine, but, “support the introduction of public health measures such as food fortification to improve vitamin D status in settings where profound vitamin D deficiency is common.”