Why the XBB.1.5 COVID variant is spreading across the US so quickly
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Just the FAQs, USA TODAY
The claim: Post implies COVID-19 vaccine increases risk of ICU admittance
“In Australia, the more doses of vaccine you’re received, the more likely you are to end up in the ICU,” reads a caption above the graph. “Is this how vaccines normally work?”
The graph, which is shown via a screenshot of a Jan. 6 tweet, is labeled “NSW Australia COVID ICU Admissions – Nov/Dec 2022.” It features five categories: “Unvaccinated,” “1 Dose,” “2 Doses,” “3 Doses” and “4+ Doses.”
The “unvaccinated” category shows zero ICU admissions. For the remaining categories, more ICU admissions are recorded as the number of doses rises.
Other social media users interpreted the graph as showing a causal connection, including one who commented, “I am constantly hearing of people dying! Yet no one else seems to notice the connection.”
The post garnered more than 3,000 likes in two weeks.
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Our rating: Missing context
The implied claim here is wrong. Vaccine efficacy cannot be determined by simply looking at the vaccine status of people admitted to the ICU in Australia, because most Australians have been vaccinated. Experts note that older and less healthy Australians are more likely to have more doses of the vaccine. Studies that account for these nuances show the COVID-19 vaccines significantly reduce the chance of hospitalization and death from COVID-19.
Vaccine efficacy cannot be determined from Australian ICU data alone
The graph cites weekly COVID-19 surveillance reports from an Australian state health authority, NSW Health, as the source of its data. However, NSW Health said the post’s message is wrong.
“There is no evidence to support the notion that vaccination increases a person’s chances of hospitalization from COVID-19,” reads a statement NSW Health sent to USA TODAY. “To the contrary, staying up to date with COVID-19 vaccinations is the most important factor in protecting against serious outcomes from infection.”
None of the November or December reports reviewed by USA TODAY matched the numbers in the graph exactly. But they did reflect the general trend shown in the graph – including zero unvaccinated COVID patients being admitted to the ICU.
“However, the relationship between vaccination and risk of serious outcomes from COVID-19 infection can no longer be determined using these surveillance data alone as most of the NSW population (95.8% of those over age 16 and nearly 100% of those older than 65) have now received at least two doses of vaccine,” reads the NSW Health statement.
Thus, the vast majority of the population would be excluded from the “Unvaccinated” and “1 Dose” categories on the graph.
“In a highly vaccinated population, absolute case numbers – such as ICU admissions – stratified by vaccination status does not make sense and can be misleading,” Dr. Onyema Ogbuagu, an assistant professor at Yale School of Medicine who studies COVID-19 vaccines and therapies, told USA TODAY in an email.
Data must be corrected for risk factors to determine vaccine efficacy
The oversimplified graph is misleading because the process of determining vaccine efficacy must account for multiple factors, Dr. Stuart Ray, vice chair of medicine for data integrity and analytics and professor of medicine at Johns Hopkins Medicine, told USA TODAY.
Assessing vaccine effectiveness requires comparing rates of complications (sickness, hospitalizations or deaths) in the vaccinated and unvaccinated populations, then adjusting for major factors that affect the risk of complications, he said in an email.
These factors can include age and underlying health conditions, both of which are complicating factors in the NSW surveillance reports.
“Given this complexity, the relationship between vaccination and risk of serious outcomes cannot be determined using these surveillance data alone,” reads the agency’s website.
As an example, the surveillance report released on Dec. 31, 2022, showed that 62% of patients admitted to the ICU in the previous two weeks had either three or more vaccine doses. But 69% of admitted ICU patients were 60 or older.
However, vaccination is clearly protective, Ray said.
“Analyses of vaccine efficacy continue to show significant – 5-fold or more – reduction in hospitalizations and death due to COVID-19 associated with vaccination, across multiple age groups,” he said. “Variations in rate of infection, changes in the virus, etc. have made such analyses complicated, but the consistency of the findings is compelling.”
Ray said the amount of time the vaccine offers protection is unknown and could range from months to years.
USA TODAY reached out to the Instagram user who shared the post for comment. The Twitter user who posted the graph could not be reached.
Associated Press also debunked the claim.
Our fact-check sources:
- NSW Health Media Statement, Jan. 17, Subject: COVID-19 vaccinations
- Dr. Onyema Ogbuagu, Jan. 24, Email exchange with USA TODAY
- Dr. Stuart Ray, Jan. 19, Email exchange with USA TODAY
- NSW Health, Dec. 31, 2022, NSW Respiratory Surveillance Report – two weeks ending 31 December 2022
- NSW Health, accessed Jan. 24, NSW respiratory surveillance reports – COVID-19 and influenza
- Associated Press, Jan. 12, Claims linking COVID vaccinations to ICU admissions are misleading
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