Why Biden's second recall wasn't enough to prevent infection
President Biden's coronavirus infection is a stark illustration that Covid vaccines, powerful as they are, fall far short of the bulletproof shields scientists once hoped for.
Mr. Biden received multiple doses of Pfizer-BioNTech vaccine; his last hit, a second encore, was on March 30. Studies suggest these doses will provide a powerful bulwark against serious illness – and indeed, the President has only mild symptoms so far after testing positive on Thursday, according to the White House.
But even booster doses offer little defense against infection, especially with newer versions of the virus. The protection they offer decreases sharply and quickly, according to several studies. In the president's case, the booster shot he received nearly four months ago likely lost most of its ability to prevent infection.
But the Omicron variant dashed those hopes. As more and more of the population acquired some immunity, whether from infection or vaccines, the virus evolved to evade these defenses. BA.1, the subvariant of Omicron that circulated during the winter, was adept at causing infections even in those who had received a booster dose a few weeks earlier.
Each subsequent avatar of the virus became even better at bypassing immunity. BA.5, which now accounts for nearly 80% of cases in the United States, is the trickiest yet. Detailed data collected in Qatar suggests that immunity against previous infections and vaccines is lowest against BA.5 compared to its predecessors.
BA.5 is also very contagious. The country registers around 130,000 cases per day on average; this number is likely a huge underestimate, as most people either test at home or don't test at all.
The number of hospitalizations has also increased over the weeks, although BA.5 does not appear to cause more severe disease than other forms of Omicron.
Given how much the virus has changed , the administration has debated the value of allowing additional shots of the original vaccine in the fall and offering a second booster for adults under 50. A Food and Drug Administration advisory group said last month that vaccine makers should adapt shots to new variants.
But it's unclear if these will arrive in time to prevent a wave of falls and whether the virus will have evolved beyond their reach again.
President Biden's coronavirus infection is a stark illustration that Covid vaccines, powerful as they are, fall far short of the bulletproof shields scientists once hoped for.
Mr. Biden received multiple doses of Pfizer-BioNTech vaccine; his last hit, a second encore, was on March 30. Studies suggest these doses will provide a powerful bulwark against serious illness – and indeed, the President has only mild symptoms so far after testing positive on Thursday, according to the White House.
But even booster doses offer little defense against infection, especially with newer versions of the virus. The protection they offer decreases sharply and quickly, according to several studies. In the president's case, the booster shot he received nearly four months ago likely lost most of its ability to prevent infection.
But the Omicron variant dashed those hopes. As more and more of the population acquired some immunity, whether from infection or vaccines, the virus evolved to evade these defenses. BA.1, the subvariant of Omicron that circulated during the winter, was adept at causing infections even in those who had received a booster dose a few weeks earlier.
Each subsequent avatar of the virus became even better at bypassing immunity. BA.5, which now accounts for nearly 80% of cases in the United States, is the trickiest yet. Detailed data collected in Qatar suggests that immunity against previous infections and vaccines is lowest against BA.5 compared to its predecessors.
BA.5 is also very contagious. The country registers around 130,000 cases per day on average; this number is likely a huge underestimate, as most people either test at home or don't test at all.
The number of hospitalizations has also increased over the weeks, although BA.5 does not appear to cause more severe disease than other forms of Omicron.
Given how much the virus has changed , the administration has debated the value of allowing additional shots of the original vaccine in the fall and offering a second booster for adults under 50. A Food and Drug Administration advisory group said last month that vaccine makers should adapt shots to new variants.
But it's unclear if these will arrive in time to prevent a wave of falls and whether the virus will have evolved beyond their reach again.
What's Your Reaction?
