Study shows dramatic decline in effectiveness of all three COVID-19 vaccines over time

At a mobile vaccine site in Miami, syringes containing the Johnson & Johnson vaccine are found in a tray. (Wilfredo Lea / Associated Press).
The Delta variant of coronavirus became the predominant strain in the United States. All three COVID-19 vaccines were no longer effective. According to a new study, vaccine efficacy was reduced by between 35% to 85% among veterans.

Researchers compared the records of almost 800,000 veterans from the United States and found that the three vaccines had roughly the same ability to prevent infection in March. This was just as the Delta variant was taking root in American communities.

However, this changed drastically over the next six-months.

Modernas two-dose COVID-19 vaccination, which was 89% effective in March and 58% by September, had only been 58% effective.

Pfizer and BioNTech vaccines' shots were effective between 87% and 45% during the same time.

Most strikingly, Johnson & Johnson's single dose vaccine saw its protective power drop from 86% down to only 13% in six months.

These findings were published in Science on Thursday.

Although the three vaccines were better at preventing COVID-19-related deaths, the Delta variant started to cause a three month surge in infections and deaths. The shots' effectiveness on this score revealed large gaps.

The risk of COVID-19 in veterans aged 65 years and older who had received the Moderna vaccine was 76% lower than that of unvaccinated veterans.

Veterans who received the Pfizer BioNTech vaccine after a breakthrough infection were 70% less likely than their non-vaccinated counterparts to die.

Older vets who received a single shot of J&J were 52% less likely than those who did not get shots to die from a breakthrough infection.

The Pfizer BioNTech and Moderna vaccines offered the greatest protection for veterans aged under 65 against fatal COVID-19 cases, with 84% and 82% respectively. Younger veterans who were inoculated by J&J vaccine were 73% less likely than their non-vaccinated counterparts to develop a breakthrough infection.

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Representatives of Johnson & Johnson did not respond immediately to inquiries to discuss the findings.

The Centers for Disease Control and Prevention recommends booster shots for anyone who has received the Johnson & Johnson vaccine less than two months ago.

Six months after the second dose of Moderna or Pfizer vaccines, boosters are recommended for all 65-year-olds; people with serious medical conditions such as COVID-19; seniors who live in group settings or nursing homes; and people who work or live in high risk settings like prisons or hospitals.

All people with compromised immune systems should get a booster shot as soon as possible if their last vaccine was effective for at least 28 days.

The new study provides the most complete comparison of the three vaccines across the country this year, with millions of Americans considering whether they require a boost.

It tracked 780.225 veterans of the U.S. Armed Forces from February 1 through October 1. Nearly 500,000 had been vaccinated while only 300,000 hadn't.

All the patients were from all over the country and received healthcare through the Veterans Affairs unified system. This system provides healthcare for 2.7% of the U.S. populace. Although the study group was diverse in ethnicity and race, the records that were used by researchers were uniform.

These were veterans so the study population included six times more men than women. They were also more senior than expected: 48% were over 65, 29% were 50-64, and 24% were below 50.

While veterans aged over 50 were more likely than younger veterans to die during the study, both the young and the old suffered from a decline in the protection provided by vaccines against disease and death.

The study was carried out by a team of researchers from the Public Health Institute of Oakland, San Francisco Veterans Affairs Medical Center, and the University of Texas Health Science Center.

Lead author of the study, Dr. Barbara Cohn said that in addition to comparing COVID-19 vaccines the analysis gives "an insight into making informed decisions about primary vaccinations, booster shots and other multiple layers protection." This includes coronavirus testing, mask mandates and other public health measures that aim to counter viral spread.

The authors stated that strong evidence points to the decline in vaccine power should encourage states and regions with high vaccination rates to retain mask mandates. The findings support the CDC's recommendation that all J&J vaccine recipients receive a booster.

Study concluded that the most damaging factor to vaccine protection was the Delta variant. This variant caused a wave of deaths and infections across the country in spring and summer.

Similar evidence has been found by other researchers. They have also suggested that immune system defenses against SARS/CoV-2 just fade with time and that waning vaccine efficacy would likely have occurred with or without the introduction of a more transmissible strain.

This story first appeared in Los Angeles Times.