AIHA May Be Rare Side Effect of COVID-19 Vaccination: Review

11 new cases were found after vaccination; 7 cases of symptom worsening

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Very infrequent cases of CAD and related conditions have developed following vaccination against COVID-19.

Although extremely rare, there have been cases of cold agglutinin disease (CAD) and related conditions following vaccination against COVID-19, a recent review study reported.

While it’s difficult to draw firm conclusions about cause and effect, scientists say developing CAD may be a very rare side effect from COVID-19 vaccines. In all reported cases, vaccine-related disease was successfully managed with standard treatments.

The review study, “Development and exacerbation of autoimmune hemolytic anemia following COVID-19 vaccination: A systematic review,” was published in the International Journal of Laboratory Hematology.

The COVID-19 pandemic has resulted in more than 500 million infections and more than 6 million deaths to date. Several vaccines are now widely available and trials have shown they can substantially reduce the risk of severe COVID-19.

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Disease Flares Due to COVID-19 Vaccines Manageable With Proper Care

More than 12 billion doses of COVID-19 vaccines have been administered so far and like other vaccines these are generally very safe and well tolerated. There have been rare reports of serious vaccine side effects, however, including instances of autoimmune hemolytic anemia (AIHA), a broad range of diseases where an autoimmune attack leads to the destruction of red blood cells.

CAD is a specific type of AIHA wherein self-reactive antibodies called cold agglutinins bind to red blood cells at low temperatures, causing them to clump together and die.

A team of scientists in Iran reviewed the scientific literature to identify all documented cases of new or worsening AIHA that arose after COVID-19 vaccination.

The review identified 11 cases of new-onset AIHA after a COVID-19 vaccine. These people ranged in age from 41–88 and about two-thirds were women.

One patient had disease-driving antibodies that were active at cold temperatures. Most had antibodies that were only active at warm temperatures, though one had antibodies active at both warm and cold temperatures.

Four of these patients received the vaccine developed by Pfizer, four were given the Moderna vaccine, and one had the AstraZeneca vaccine. Scientists noted that the mRNA-based Pfizer and Moderna vaccines have been more commonly used, which likely explains this difference in distribution.

In almost all of these patients, AIHA developed within a few weeks of the first or second dose of the vaccine. In one case, AIHA developed four months after the second dose and in another case, it developed after a booster.

The review also identified seven people, ages 33–79, who had pre-existing AIHA and whose symptoms worsened after receiving the vaccine. Three had CAD, while the other four had antibodies active at warm temperatures.

Four received the Moderna vaccine, two the Pfizer one, and in the last case the specific vaccine maker was not reported. The exacerbations occurred after the first vaccine dose in four people, after the second dose in two, and after the booster in one.

In all these cases, AIHA symptoms were successfully managed with standard steroid and blood transfusion treatments, the researchers noted.

Although they emphasized that it’s impossible to draw firm conclusions from these data, the researchers concluded that “AIHA may be considered as a very rare complication of COVID-19 vaccination that occurs following vaccination.”