COVID-19

Over one million people have died from COVID-19 in the United States. Thousands of people continue to become infected with the SARS-CoV-2 virus, are hospitalized with serious illness, and die from COVID-19. However, due to vaccines, therapeutics, and past COVID infections, the risk has decreased for severe illness and death from COVID (COVID Act Now, 2023).

The SARS-CoV-2 virus that causes COVID-19 is also constantly mutating. In the majority of cases, when mutations take place, they are inconsequential because the protein configuration of the virus does not change. These are small changes (referred to as “drift”), and the immune system is able to recognize and respond to such changes. However, there may also be abrupt, significant changes in the structure of a virus (referred to as “shift”). If the configuration of a virus mutates enough, the virus may respond differently to treatments, or the antibodies of the immune system may not recognize the new mutation, resulting in infection.

Although antibodies created after COVID-19 vaccination will recognize and respond to many mutations of the virus, the immune system may not recognize and respond to all mutations, which necessitates the development of updated booster vaccines (Nightengale, 2021).

COVID vaccines will transition from government purchase to the commercial market in the fall of 2023. For optimal protection, the CDC recommends COVID-19 vaccines for everyone 6 months of age and older.

2023–2024 COVID-19 Vaccine Updates

In June 2023, FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) made recommendations on SARS-CoV-2 strain to be included in updated COVID-19 vaccines for use in the United States beginning in the fall of 2023. The committee unanimously voted that the vaccine composition be updated to a monovalent COVID-19 vaccine with an Omicron/XBB.1.5 subvariant, and the FDA advised manufacturers to develop COVID booster shots with that composition (FDA, 2023c).

In September 2023, the FDA approved and authorized for emergency use those updated COVID-19 vaccines formulated to more closely target currently circulating variants and to provide better protection against serious consequences of COVID-19, including hospitalization and death.

• Individuals 5 years of age and older regardless of previous vaccination are eligible to receive a single dose of an updated mRNA COVID-19 vaccine at least 2 months since the last dose of any COVID-19 vaccine.
• Individuals 6 months through 4 years of age who have previously been vaccinated against COVID-19 are eligible to receive one or two doses of an updated mRNA COVID-19 vaccine. Unvaccinated individuals 6 months through 4 years of age are eligible to receive three doses of the updated authorized Pfizer-BioNTech COVID-19 vaccine or two doses of the updated authorized Moderna COVID-19 vaccine.

The FDA is confident in the safety and effectiveness of these updated vaccines, and the agency’s benefit-risk assessment demonstrates that the benefits of these vaccines for individuals 6 months of age and older outweigh their risks.

Individuals who receive an updated mRNA COVID-19 vaccine may experience similar side effects as those reported by individuals who previously received mRNA COVID-19 vaccines as described in the respective prescribing information or fact sheets.

The updated vaccines are expected to provide good protection against COVID-19 from the currently circulating variants. Barring the emergence of a markedly more virulent variant, the FDA anticipates that the composition of COVID-19 vaccines may need to be updated annually, as is done for the seasonal influenza vaccine (FDA, 2023e).

In line with the FDA approvals described above, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) updated their COVID-19 vaccine recommendations:

• Everyone ages 6 years and older should receive one updated Pfizer-BioNTech or Moderna COVID-19 vaccine to be up to date.
• People ages 65 years and older may get a second dose of updated Pfizer-BioNTech or Moderna COVID-19 vaccine.
• People who are moderately or severely immunocompromised may get additional doses of updated Pfizer-BioNTech or Moderna COVID-19 vaccine.
• Children ages 6 months to 5 years may need multiple doses of COVID-19 vaccine to be up to date, including at least one dose of updated Pfizer-BioNTech or Moderna COVID-19 vaccine, depending on the number of doses they’ve previously received and their age.

The CDC’s COVID-19 vaccine recommendations will be updated as needed (see “Resources” at the end of this course).

Impact of COVID-19 Vaccination on General Health

Results of vaccine effectiveness (VE) studies are critical to the CDC’s vaccine program and national vaccine policy decision-making. The CDC has published the following findings about vaccine effectiveness in adults:

• The original monovalent (ancestral SARS-CoV-2 strain) mRNA vaccination was 76% effective in preventing COVID-19–associated invasive mechanical ventilation and death up to 6 months after the last dose and remained 56% effective at 1–2 years.
• Among adults aged ≥18 years without immunocompromising conditions, bivalent (ancestral and BA.4/BA.5 strains) vaccine effectiveness against COVID-19–associated hospitalization declined from 62% at 7–59 days postvaccination to 24% at 120–179 days compared with VE among unvaccinated adults. Among immunocompromised adults, lower bivalent booster VE was observed. However, bivalent booster VE was sustained against critical COVID-19-associated outcomes, including intensive care unit admission or death.
• Among nursing home residents who were up to date with COVID-19 vaccination (most had received a bivalent vaccine), vaccine effectiveness against SARS-CoV-2 infection was 31.2%.
• Both the original (monovalent) mRNA COVID-19 vaccine series and the bivalent vaccine provide protection against COVID-19–associated emergency department and urgent care visits in children ages 6 months to 4 years (Pfizer-BioNTech) and 6 months to 5 years (Moderna).
  (CDC, 2023k)

A group of National Institutes of Health (NIH)–supported researchers found a significantly low incidence of severe COVID-19 illness among more than 1.6 million veterans who had been vaccinated and boosted. Over a 24-week follow-up for each fully vaccinated participant, the following results were reported:

• Individuals with an immune-compromising condition had a very low rate of hospitalization or death. In this group, 39.6 per 10,000 people had a serious breakthrough infection.
• For those participants who had preexisting health conditions, hospitalizations or deaths totaled 0.07%.
• In adults 65 years of age or younger who had no high-risk conditions, hospitalizations or death totaled less than 0.01%.
• Participants who had received boosters as well as the primary vaccinations and who were among the high-risk groups with comorbidities seemed to be protected against even some emergent variants.
  (Kelly et al., 2022)

The World Health Organization (WHO) has stated that COVID-19 vaccines have saved millions of lives and provide strong protection against serious illness, hospitalization, and death. To ensure that protection is maximized, the WHO encourages people to receive COVID-19 vaccine doses and boosters as recommended by medical authorities (WHO, 2023).