By Dr. Max Hammonds

As if it weren’t enough that we are dealing with the COVID-19 pandemic, the season for catching the flu is now upon us.

Yes, you should be getting your flu shot. Every year the virologists around the world work together to come up with the best guess – an educated guess – as to what vaccine to put together to protect against the next year’s probable influenza viruses. Throughout the year, they follow closely the mutations that they see happening in the three common viruses that cause human influenza. Type A has many subtype species which mutate quickly and are responsible for most of the flu pandemics over the past century. Types B and C have only one species that infects humans, but they also mutate from year to year. Therefore, an individual cannot count on their own immunity developed from last year’s vaccine to protect them from this year’s newest strains.

The flu vaccine for each year is a new combination to cover all three types of viruses in their newest mutational form. The vaccine comes in three forms: nasal spray (only for those over two years old to 50 years old and who are not pregnant or do have severe illness or are immunocompromised), intramuscular injection of regular dose for all other people, and intramuscular injection of high dose (four times concentration) for those over 65 years old.

Is contracting the influenza virus a serious matter? We measure the seriousness of an infectious illness by three variables: how easy is it to catch (how infectious), how virulent (how seriously ill do people usually become), and how deadly (how many people die)? The flu is highly infectious, especially Type A. Most people find that the symptoms of the flu are very uncomfortable, especially the general body ache and the high fever. While they generally recover in 5-7 days or less, serious complications can result from the flu, including pneumonia, encephalitis (inflammation of the brain) and worsening of underlying heart or pulmonary problems. 

Less than one in a thousand infected people die (0.1%) from the flu, but because it is so highly infectious, in those not vaccinated, the infection rate can be 50-70% and, therefore, the deaths can happen in large numbers. In the world population, 250,000 to 650,000 die each year from the flu, most in those over 65 or under 2 years of age, in those with severe underlying illnesses, and in those who are seriously immune compromised. In the United States, the yearly average is 36,000 deaths per year due to the flu.

And yes, the symptoms of the flu are very much like the COVID-19 symptoms in the beginning. Headache, sore throat, body aches, and fever. This is usually followed by cough and (usually in children) vomiting/diarrhea. Severe flu can look like COVID-19 with pneumonia, chest pain, confusion and dizziness, and a rash – and as a secondary complication bacterial pneumonia and hemorrhage. The unique symptoms of COVID-19 are the loss of the sense of taste and smell and increased clotting throughout the body (rather than hemorrhage). Both influenza and COVD-19 can cause the body to over-react in its efforts to mount an immune response, resulting in a rapid self-attack on the major body organ systems (cytotoxic storm).

Does the influenza vaccine protect against COVID-19? No. The two viruses are from totally different families and have different outside protein coats. However, the influenza vaccine is known to cross-react with some other viral diseases and provide some protection, perhaps by stimulating the body’s immune system to higher level of readiness and mitigating the symptoms and length of time a person is sick from these other viral illnesses. The same may be true for a cross-reaction of the influenza vaccine and COVID-19. (There is some evidence of this happening in the southern hemisphere of the world where their winter flu season has been ongoing since March-April).

How do you protect yourself against contracting the flu? The same as for any other respiratory moisture particle, air-borne virus – wearing a mask, social distancing, hand washing, frequent cleaning of surfaces touched by others. Yes, Tamiflu (an anti-viral medication) can shorten the course of the illness, but it won’t keep you from catching the flu and it doesn’t decrease the risk of complications. No, Tamiflu does not work against COVID-19.

Conclusion: You don’t want to be fighting the flu and COVID-19 at the same time. And you don’t want your medical care professionals to have to wonder which disease you might be suffering from. Since we now have two diseases that spread by exactly the same mechanisms, we would be smart to continue our COVID-19 precautions: masks, social distancing, hand washing. And since we have a vaccine against the flu that is 25-60% effective (depending on the year), we would be prudent and wise to get our flu shot this year, for sure.

Dr. Max Hammonds, MD (retired) MPH