Immunization

Vaccination is the most important measure to protect against influenza and its complications.8 According to the CDC, 45% of adults and 63% of children receive the flu vaccine annually.9 This leaves a large portion of the population at risk for infection.  Increases in the number of people, especially at-risk populations, being vaccinated against the flu would decrease the disease burden on the population and the stress on the health care system.1 This is especially important during the COVID-19 pandemic, which continues to put stress on available health care resources.

The CDC and WHO recommend influenza vaccines for everyone aged ≥6 months, with a special focus on the following high-risk populations and their contacts/caregivers10:

  • Children aged 6 to 59 months and adults aged ≥50 years
  • People with chronic pulmonary, cardiovascular (excluding isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders
  • People who are immunocompromised
  • Women who are or will be pregnant during the influenza season
  • Children and adolescents receiving aspirin- or salicylate-containing medications
  • Residents of nursing homes and other long-term care facilities
  • American Indians/Alaska Natives
  • People who are extremely obese (body mass index ≥40)

It is important to remember that children aged 6 months to 8 years require 2 doses of vaccine, given at least 4 weeks apart, their first season receiving a vaccination.10


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Several influenza vaccines are available in the United States: standard-dose inactivated influenza vaccine, high-dose inactivated influenza vaccine, adjuvanted influenza vaccine, recombinant influenza vaccine, live attenuated influenza vaccine, and cell culture–based inactivated influenza vaccine. Recommended timing for administration of seasonal influenza vaccine is during September and October.11 However, vaccination should continue as long as viruses are circulating and vaccines are available.10 

The Advisory Committee on Immunization Practices does not anticipate a major change in the recommendation or timing of the flu vaccine because of the COVID-19 pandemic and does not recommend early vaccination in July or August against influenza because this can lead to a decreased protection in the later part of the flu season.11 The CDC is working with health care providers and state and local health departments to develop contingency plans on how to vaccinate people against flu without increasing the risk for exposure to COVID-19.11

Two new vaccines have been approved for the 2020-2021 influenza season: quadrivalent high-dose vaccine for use in adults ≥65 years of age (replaces the trivalent high-dose vaccine) and quadrivalent adjuvanted vaccine for use in adults ≥65 years of age (similar to previous trivalent adjuvanted vaccine).10 Both vaccines have been shown to promote a better immune response to the vaccine in adults ≥65 years of age.10

Nonpharmaceutical Interventions

Both COVID-19 and influenza are spread primarily through respiratory droplets during close contact.1 Social distancing aims to reduce the frequency of contact and increase the physical distance between people, which reduces person-to-person transmission. For influenza, CDC guidelines recommend at least 3 feet between persons. This guideline applies to apparently healthy individuals as well. Continuing other social distancing measures, such as teleworking and avoiding mass gatherings, also will help decrease the spread of influenza.6

Like COVID-19, influenza can be transmitted by people with mild or asymptomatic infections12 A challenge associated with isolation of potentially infective individuals is the lack of evidence about the duration of infectivity.7 CDC guidelines recommend voluntary isolation until fever is absent for 24 hours or 5 to 7 days after illness onset. Temperatures should be checked in the absence of antipyretic medications.6

Isolation or quarantine of infected and exposed individuals reduces transmission of illness in the community but increases transmission of infection to household contacts. Models show that an estimated 25% to 40% of H1N1 cases in the 2009 pandemic were attributed to household transmission.13 Voluntary/self-quarantine is preferred over mandatory quarantine because the latter raises ethical concerns about freedom of movement and the increased risk for infection among quarantined individuals.7

The continued use of face coverings in public for prevention of COVID-19 also will help limit the spread of influenza. Masks provide a physical barrier for large-particle respiratory droplets when an infected person talks, coughs, or sneezes. Verma and colleagues studied the dispersal of respiratory droplets with and without non-medical face masks.14 Masks perform better when they are well fitted to a person’s face; if not, the respiratory droplets leak from the top and bottom of the mask, in addition to the expected transmission through the mask. A well-fitted multilayer mask made of quilted fabric decreased droplet dispersal to 2.5 inches compared with 8 feet without a mask; 3 feet, 7 inches with a bandana; 1 foot, 3 inches with a folded handkerchief; and 8 inches for an off-the-shelf cone style mask.14 Regardless of mandatory mask requirements, well persons who are at high risk from influenza complications and cannot avoid crowded settings benefit from wearing a mask.6

This article originally appeared on Clinical Advisor