COVID-19 Vaccines Past and Present

US Pharm. 2024;49(4):30-31.

COVID-19 is a coronavirus that spreads primarily from close contact with another individual with COVID-19. People are typically infected from the respiratory droplets of infected people. They may also be infected by touching a surface or object that has the virus on it and then touching their mouth, nose, or eyes; however, this is proven to be less common than initially believed.¹ Many countries have recently seen multiple waves of COVID-19, each causing a range of reactions to the virus.

The World Health Organization (WHO) still believes that COVID-19 originated in Wuhan—the Chinese city where the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified—and expanded across China and abroad. By tracing the virus’ path, the WHO tried to help prevent future viral spillovers.¹

Many scientists think that COVID-19 may have originated in bats; however, the origin of transference to humans is still unknown. Other coronaviruses have passed from an intermediate animal host; for example, the virus that caused an outbreak of severe acute respiratory syndrome in 2002–2004 is believed to have been spread to people from civets.¹

Searching for and confirming the origins of a virus can take years—if it can be done at all. The COVID-19 investigation will have to navigate through the highly sensitive political situation between China and the United States. The coordination between these two countries has created a more positive environment to conduct collaborative research in this field and resolve the issue worldwide.^1-3

Since the appearance of the COVID-19 infection in 2019, millions of COVID-19 vaccines have been given, starting in December 2020. The incident was declared a pandemic by the WHO in March 2020, and by April 19, 2021, the entire U.S. had opened vaccine eligibility to residents aged 16 years and older.^1-3

COVID-19 Vaccines

Two types of COVID-19 vaccines are currently available in the U.S.: messenger RNA (mRNA) vaccines and protein subunit vaccines.

The first two vaccines made available in the U.S.—one developed by Pfizer-BioNTech and the other by Moderna—work via a novel mRNA mechanism. In these vaccines, the mRNA carries instructions to make the coronavirus spike protein—the prickly projections on the surface of the virus. The immune system then builds an immune response against the protein, thereby learning how to protect against future infection.

A third vaccine, developed by Johnson & Johnson (J&J)/Janssen, received an Emergency Use Authorization from the FDA on February 27, 2021. Unlike the Pfizer and Moderna vaccines, which store instructions on single-stranded mRNA, the J&J vaccine used double-stranded DNA. U.S. regulators revoked emergency authorization for J&J’s COVID-19 vaccine after the company requested its withdrawal in May 2023. This was due to a syndrome called vaccine-induced immune thrombotic thrombocytopenia.^1,3

The current COVID-19 vaccines recommended for use in the U.S. are Pfizer-BioNTech, Moderna, and Novavax.^2,3

Updated COVID-19 Vaccines

As of September 12, 2023, the 2023–2024 updated Pfizer-BioNTech and Moderna COVID-19 vaccines were recommended by the CDC for use in the U.S.

As of October 3, 2023, the 2023–2024 updated Novavax vaccine was also recommended by the CDC for use in the U.S.

The updated COVID-19 vaccines (2023–2024 formula) more closely target the XBB lineage of the Omicron variant and could restore protection against severe COVID-19 that may have decreased over time. It is anticipated that the updated vaccines will be better at fighting currently circulating variants.

There is no preferential recommendation for the use of any one COVID-19 vaccine over another when more than one licensed or authorized, recommended, and age-appropriate vaccine is available.^3,4

Bivalent Vaccines

The 2022–2023 bivalent vaccines were designed to protect against both the original virus that causes COVID-19 and the Omicron variants BA.4 and BA.5. Two COVID-19 vaccine manufacturers, Pfizer-BioNTech and Moderna, had developed bivalent COVID-19 vaccines.

As of September 11, 2023, the bivalent Pfizer-BioNTech and Moderna COVID-19 vaccines are no longer available for use in the U.S.^3,4

Original Vaccines

As of April 18, 2023, the original Pfizer-BioNTech and Moderna COVID-19 vaccines are no longer available for use in the U.S. As of May 6, 2023, the J&J/Janssen COVID-19 vaccine is no longer available for use in the U.S.

The first COVID-19 vaccines were called “original” because they were designed to protect against the original virus that causes COVID-19.^3-6

Children’s COVID-19 Vaccination

Individuals aged 5 years and older should get one dose of an updated COVID-19 vaccine to protect against serious illness from COVID-19.

Children aged 5 to 11 years who are unvaccinated or have previously received a COVID-19 vaccine before September 12, 2023, should get one updated Pfizer-BioNTech or Moderna COVID-19 vaccine.

Individuals aged 12 years and older who are unvaccinated should get either one updated Pfizer-BioNTech or Moderna COVID-19 vaccine or two doses of updated Novavax COVID-19 vaccine.

Individuals aged 6 months and older who were vaccinated outside the U.S. should receive at least one dose of an updated COVID-19 vaccine regardless of past COVID-19 vaccination history (e.g., vaccine types, vaccine manufacturers, number of doses) unless they received an updated COVID-19 vaccine that is FDA approved or authorized (i.e., Moderna, Novavax, Pfizer-BioNTech).^3-6

Vaccine Authenticity

Pfizer-BioNTech and Moderna are working to distribute updated COVID-19 vaccines safely and efficiently. At this time of this writing, there is no COVID-19 vaccine produced by any manufacturer that is available for purchase by individuals. One should not accept offers for COVID-19 vaccinations that do not come from authorized sources. Such sources are healthcare providers, pharmacies, or a local government health agency.³

People who have recently had COVID-19 infection still need to stay up to date with vaccines but may consider delaying their vaccine by 3 months.³

REFERENCES1. Saljoughian M. COVID-19: a closer look. US Pharm. 2021;45(4):4-7.
2. New England Journal of Medicine. COVID-19 Vaccine Resource Center. March 29, 2023. www.nejm.org/covid-vaccine. Accessed January 4, 2024.
3. CDC. Stay up to date with COVID-19 vaccines. January 18, 2024. www.cdc.gov/coronavirus/2019-ncov/vaccines/stay-up-to-date.html. Accessed Feburary 27, 2024.
4. Oliver SE, Gargano JW, Marin M, et al. The Advisory Committee on Immunization Practices’ interim recommendation for use of Pfizer-BioNTech COVID-19 vaccine—United States, December 2020. MMWR Morb Mortal Wkly Rep. 2020;69(50);1922-1924.
5. Oliver SE, Gargano JW, Marin M, et al. The Advisory Committee on Immunization Practices’ interim recommendation for use of Moderna COVID-19 vaccine—United States, December 2020. MMWR Morb Mortal Wkly Rep. 2021;69(5152);1653-1656.
6. CDC. Use of COVID-19 vaccines in the United States. October 6, 2023. www.cdc.gov/vaccines/COVID-19/clinical-considerations/COVID-19-vaccines-us.html. Accessed February 27, 2024.

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

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