Researchers say COVID-19 vaccines have proven to be effective as well as safe. Pedro Portal/El Nuevo Herald/Tribune News Service via Getty Images
- In a new study, researchers say COVID-19 vaccines were shown to be effective against all variants of the novel coronavirus.
- In another study, researchers say side effects from the vaccines were for the most part mild and short-lived.
- Experts say the new research indicates the need for constant surveillance and the potential need for booster doses if new variants emerge.
New research backs up what many experts reported seeing during the height of the Omicron surge over the winter.
Booster vaccine doses of the two mRNA vaccines — Pfizer and Moderna — were necessary to adequately protect people from the latest dominant variant.
The protection is so important that some experts would like the Centers for Disease Control and Prevention (CDC) to change the current definition of what it means to be “fully vaccinated.”
This comes as more research concludes that most side effects from the nearly 300 million mRNA COVID-19 vaccine doses administered during the first 6 months they were available were mild and resolved within a few days.
That same research also offers validation to those who found the second shots of an mRNA vaccine produced short-term but noticeable side effects, including body aches, fever, and other flu-like symptoms.
A look at effectiveness
The research on vaccine effectiveness, published in the British Medical Journal, also provides insight into vaccination schedules as the virus that causes COVID-19 continues to mutate and potentially develop new defenses around the vaccines.
Researchers from top universities and medical institutions across the United States looked at the records of nearly 12,000 adult patients admitted to 21 hospitals between March 2021 and Jan. 2022. Of those patients, more than 5,700 tested positive for COVID-19.
The researchers looked at how well vaccine effectiveness fared with either the Alpha, Delta, or Omicron variants.
The Omicron surge peaked at about 807,000 new cases a day in mid-January, or weeks after the traditional end-of-the-year holiday season.
In the United States and the rest of the Northern Hemisphere, that means winter weather and gathering indoors provided an opportunity for the highly infectious omicron variant to run rampant, namely among the unvaccinated.
Using a scale developed by the World Health Organization (WHO) to gauge how sick a person becomes in the hospital, researchers discovered two doses of an mRNA vaccine gave someone a 65 percent chance of not needing to be hospitalized for COVID-19 symptoms during the Omicron wave.
Additionally, three doses gave them an 85 percent chance — the same as two doses gave them against the Alpha and Delta variants.
Despite the study being observational — meaning they can’t draw a clear line between cause and effect — the research team concluded that mRNA vaccines “were associated with strong protection against hospital admissions with COVID-19 due to the Alpha, Delta, and Omicron variants.”
Researchers also said that a booster shot “is critical for protecting populations against COVID-19-associated morbidity and mortality.”
The researchers say as the novel coronavirus continues to evolve, studies like theirs that evaluate vaccine effectiveness will be necessary, including surveillance programs that identify new variants.
Experts weigh in
Jagdish Khubchandani, PhD, a professor of public health science at New Mexico State University, said the study was done in “a nearly real-world setting” and confirms what the world saw during the Omicron surge this winter.
In general, he said, the Omicron variant is less lethal compared to the previous variants, but two doses are not as adequate for Omicron compared to Alpha and Delta.
“So, the boosters seem to be an appropriate strategy, and my guess is that if we have more variants in the future, additional doses may be required,” Khubchandani told Healthline. “It could also be possible that by the time the Omicron variant surged, immunity dwindled in individuals vaccinated during the earlier phases of the rollout, necessitating a booster dose.”
While all clinical research has limitations, Khubchandani said the ones in the BMJ study are “relatively minor.”
“Even to a varying extent, the mRNA vaccines certainly provide protection against severe infection, hospitalization, and death,” he said.
Dr. David M. Cutler, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, California, says there’s now no doubt that the COVID-19 vaccines prevent illness, hospitalization, and death.
But he added that it’s “truly unfortunate” that we continue to label a third dose — or second, for the non-mRNA Johnson & Johnson shot — as a “booster” dose.
“This word suggests extra or unnecessary, when in fact it is quite essential to preventing illness, hospitalization, and death,” Cutler told Healthline. “Unfortunately, the CDC definition of ‘fully vaccinated’ still means only two mRNA vaccines and one J&J vaccine. This recent study and many others have demonstrated that full protection come only with getting a booster.”
Dr. Fady Youssef, a pulmonologist, internist, and critical care specialist at MemorialCare Long Beach Medical Center in California, said one critical point the new research doesn’t point out is regarding patients with no symptoms or mild symptoms who were not hospitalized.
“That’s an important point to account for, given by most accounts Omicron was more transmissible but resulted in lower hospitalizations,” he told Healthline.
Youssef says the study further supports that mRNA vaccines have offered “significant protection” against severe and critical COVID-19 illness and death.
“While patients who were infected with COVID during the Omicron variant surge and required hospitalization had better outcomes than those hospitalized during the Delta variant surge, they had similar mortality to patients hospitalized during the Alpha variant surge,” he said. “So while the Omicron variant resulted in milder disease and lower hospitalization rates, those who developed moderate to critical illness secondary to COVID during the Omicron surge still had significant mortality and morbidity.”
Looking at safety
Meanwhile, the new peer-reviewed meta-analysis that appeared in the journal The Lancet Infectious Diseases suggests the data collected under the federal government’s vaccine reaction reporting system supported the clinical data that bolstered the overall safety of the vaccines.
The study data shows that the Moderna and Pfizer doses given to people remain, overall, remarkably safe.
The researchers looked at data from the nearly 8 million people enrolled in the CDC’s v-safe program, which it developed specifically for the COVID-19 vaccines. They found that less than 1 percent of participants — 56,647 after dose one and 53,077 after dose two — reported the need to seek medical care.
The Lancet study — which was designed and carried out by CDC researchers — reports that slightly more than 1 percent of the more than 340,000 adverse events reported were deaths, of which 80 percent were among people 60 or older.
Researchers noted that because the vaccines were given emergency use authorization (not full Food and Drug Administration approval), healthcare professionals “are required to report deaths and life-threatening adverse health effects after COVID-19… regardless of the potential direct association.”
The study authors note that “we found no unusual patterns in cause of death among the death reports received.”
The study’s author, Dr. David Shay, an infectious disease researcher at the CDC, said the rapid pace at which the COVID-19 vaccines were developed was “unprecedented.” Still, the researchers found the deaths in that population followed “similar patterns of deaths rates for people in this age group following other adult vaccinations.”
