HIV Patients Lose Seroprotection Before Vaccine Boosters Are Due

January 24, 2014

By Lorraine L. Janeczko

NEW YORK (Reuters Health) Jan 24 - Vaccine-induced antibodies may wane more quickly than usual in patients with HIV, who might therefore lose their protection before they receive a booster, if current guidelines are followed, new research suggests.

"Although reports in the medical literature had already suggested that the immunity conferred by vaccines may wane more quickly in patients with HIV, the necessity and optimal timing of booster doses were not clearly defined," wrote lead author Dr. Solen Kerneis, of the Paris Descartes University in Paris, France, in an email to Reuters Health.

"As expected, our analyses confirmed that the duration of seroprotection was shorter in HIV-infected patients. However, we were surprised by the particularly low rates of seroprotection estimated for certain vaccines, for example against hepatitis B, with which fewer than 50% of those who had initially responded to the vaccination maintained protective antibody titers after only two years," she wrote.

To help guide recommendations on revaccinations in people with HIV, Dr. Kerneis and her colleagues reviewed the literature on routinely recommended vaccines and estimated how seroprotection decreases over time among those who initially respond to immunization.

They searched English-language PubMed and MEDLINE articles up to January 2013 for original experimental or observational studies on most licensed vaccines that reported antibody titers beyond six months after the last dose in patients living with HIV.

Of the 159 potentially relevant studies, they reviewed 54 and accepted 19 for meta-analysis. The median number of patients in each study was 40. The median follow-up ranged from nine months to nine years after the last vaccine dose.

They fit their data using log binomial generalized linear models, pooled the predicted percentages of seroprotected patients two and five years after immunization in a meta-analysis, and reported their results online January 10 in Clinical Infectious Diseases.

HEPATITIS B: The authors found that 47% of primary responders (95% CI, 25%-70%) would be expected to maintain protective antibody titers two years after vaccination, and only 17% (95% CI, 3%-36%) after five years.

Due to the high prevalence and severity of chronic hepatitis B in HIV-infected people, they advise that hepatitis B surface antibodies (anti-HBs) be measured yearly in adults and every two to five years in children who are in close contact with hepatitis B surface antigen (HBsAg)-positive people or who are living in a high-endemicity country. Anti-HBs titers could be more closely monitored in people with the lowest antibody titers at the end of their vaccination course (10 to 100 IU).

HEPATITIS A: Overall, 92% (95% CI, 89%-95%) would be expected to maintain protective antibody titers after two years, and 81% (95% CI, 75%-87%) after five years.

Because by five years after immunization, almost 20% of primary responders would have lost their seroprotection, the authors recommend that people at increased risk for hepatitis A should have their anti-hepatitis A virus (HAV) antibodies monitored every five years. This includes travelers, men who have sex with men, drug users, people at occupational risk for HAV infection, and patients with chronic liver disease.

MEASLES: Data on adults were scarce and conflicting. For HIV vertically infected children, protective antibody levels would be expected to persist in an estimated 68% (95% CI, 42%-89%) of primary responders after two years, and in 39% (95% CI, 9%-75%) after five years.

In children with undetectable HIV viral load, the first vaccination should include two doses, ideally given after the start of highly active antiretroviral therapy (HAART), to improve maintenance of seroprotection against measles. Children vaccinated before they begin HAART and/or children with detectable HIV viral load when immunized could be given a third dose two to five years after the primary vaccination, when CD4-cell count is >200 or >15%.

TETANUS: Overall percentages of seroprotection would pbe expected to be 74% (95% CI, 57%-87%) and 43% (95% CI, 21%-66%) at two and five years after immunization, respectively.

Around 75% of HIV-infected children would be expected to maintain protective concentrations after two years, and retrospective studies showed percentages of seroprotection around 70% to 80% after five years, making 10-year intervals between boosters seem reasonable, the authors wrote.

Dr. Kerneis advised in an email that "because of the greater incidence and severity, prevention of infectious diseases in patients with impaired immunity, such as those living with HIV, is critical. Vaccination is a very important tool and clinicians should be alerted to the importance of updating immunizations and monitoring antibody titers after vaccination."

"However," she added, "an important limitation of our work is that antibody response is only one component of the immune response to vaccines. Loss of antibodies does not necessarily imply loss of clinical protection. Immune memory can persist, even in individuals with low antibody concentrations."

Dr. Alberto Cagigi of Bambino Gesu Children's Hospital at the University of Rome Tor Vergata in Rome, Italy, wrote in an email, "This is a useful review article, the results of which confirm the need for personalized vaccination schedules and compressed booster vaccine doses in patients with rapidly waning immunity. For this purpose, clinicians must perform antibody monitoring for HIV-infected individuals." Dr. Cagigi was not involved in the study.

SOURCE: http://bit.ly/19SBEjR

Clin Infect Dis 2014.

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