Tdap well tolerated in over-65s

Off-label use of tetanus-diptheria-acellular pertussis (Tdap) vaccine in senior patients results in no more adverse events than the tetanus and diphtheria (Td) vaccine, a US study shows.

The authors say they hope the findings will encourage physicians to follow the US Centers for Disease Control and Prevention (CDC) guidance to immunize all those over 65 years old.

"We found there was no increased risk of serious adverse events following Tdap, either compared with the risk following Td or with the risk in a self comparison period," say Hung Fu Tseng (Kaiser Permanente, Pasadena, California) and colleagues.

The authors compared data on 119,573 patients aged 65 years or older who received Tdap vaccine from January 2006 to December 2010 with an equal number who received Td vaccine. The frequency of prespecified vaccine-related adverse events (meningitis, encephalitis, encephalopathy, cranial nerve disorders, brachial neuritis, paralytic syndromes, medically attended inflammatory or allergic events, and anaphylaxis and generalized reaction) was assessed.

There was no significant difference between Tdap- and Td-vaccinated patients in the incidence of any prespecified events except for anaphylaxis and generalized reaction, for which Tdap vaccine conferred at 3.72-fold increased risk.

However, when the authors reviewed individual patient medical records they found only two cases of generalized reaction in the Tdap group and one case in the Td group, with no incidences of anaphylaxis.

The authors also examined events in patients in the follow-up period compared with a comparison period in the prior year. Patients were 1.59 times more likely to experience a medically attended inflammatory or allergic event after Tdap vaccination, and 7.33 times more likely to experience anaphylaxis or a generalized reaction compared with the comparison period. This is in line with expected injection-site reactions for Tdap vaccination, say Tseng and colleagues.

Furthermore, these findings are consistent with the effects of Tdap vaccination in younger populations.

While the CDC has recommended vaccination in senior patients, so far, data on Tdap's safety in this population have been limited, the authors explain in Clinical Infectious Diseases.

"Pertussis immunization is important, particularly since one of the most common sources of pertussis is infants and their relatives, including their grandparents," said Tseng in a press statement.

"We suggest that clinicians follow CDC's recommendation and talk to older adult patients about vaccination against pertussis to protect themselves and their family members."

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