Four months ago in Mountain Medicine, October 3, 2018, Dr. Kelsey Allen reviewed the benefits of influenza vaccination. You are far less likely to develop influenza, but if you do, you are likely to have a milder illness. Today’s column updates influenza activity in Oregon and reviews progress in vaccine development and advances in management of influenza.
Flu is a common illness; between 5-20% of the U.S. population will become infected each year. In the week ending January 26, 2019, the CDC reported Oregon had “widespread influenza activity”. Oregon emergency department visits for influenza-like illness doubled since the beginning of flu season, and more than 2800 confirmed influenza test results have been reported to the CDC from Oregon. Of six Oregon geographic regions, the eastern region, including Wallowa County, had the highest percentage of clinic and emergency room visits for influenza-like illness.
Peak influenza activity may occur as late as March before trailing off in April. Consequently, Oregon influenza season may be just beginning. It takes 2 weeks for flu vaccine to produce effective antibodies, so you may be protected if the worst is yet to come. Vaccination of children, the elderly and those with chronic diseases is especially important. These are vulnerable populations most likely to have severe complications.
Your local health care provider will select the most appropriate vaccine based on age, pregnancy status, allergies and immune status. For example, those over 70 years will likely receive “high-dose” vaccine, found to be significantly more effective in boosting antibody response and preventing influenza in elderly compared to standard vaccines.
Months before endemic influenza appears in the northern hemisphere the vaccine composition is selected to allow for manufacturing and distribution. Over 90% of Oregon cases have been caused by influenza A (H1N1), and the H1N1 strain is included in all vaccines. Two additional strains are included in the trivalent vaccines, Influenza A (H3N2) and an influenza B strain. Current vaccines are less than 100% protective because unexpected strains may arise, or because the circulating strain can slightly change so that vaccine-induced antibodies are unable to completely neutralize the virus.
The current vaccines need improvement, but don’t be dissuaded. The 50-60% likely to be protected will not transmit the virus to friends and family, nor to the most vulnerable. If you do develop influenza, because your illness is likely less severe you are also significantly less likely to need hospitalization or require antiviral and antibacterial drugs. These are not trivial benefits.
The search for a universal flu vaccine--a vaccine requiring a single injection that neutralizes all strains of influenza --is beginning to bear fruit. Some vaccines are in the final stages of clinical testing, though marketing may be far off.
Not all research and development is focused on vaccines. Improved diagnostic tests are 95% sensitive in confirming influenza within 15 minutes. Anti-influenza drugs, some requiring a single dose, shorten the duration of illness and possibly prevent deaths. The benefit of antiviral drugs is greatest within 2 days of symptoms onset; early treatment is critical.
The bottom line? A century ago the January 30, 1919 Wallowa County Chieftain reported that the opening of the new O.K. Theater had been delayed by more than 6 weeks because of “the influenza”. In contrast, the 2018/2019 flu season in Wallowa is characterized by a large network of scientists and clinicians at national institutes (NIH) and Centers (CDC), vaccine and drug manufacturers, Oregon epidemiologists and public health workers, clinical laboratories and local health care providers who are all committed to keeping us healthy during influenza season. All we have to do is get vaccinated.