Single doses of H1N1 flu vaccine for adults, adolescents starting at age 10, and pregnant women are among the latest recommendations issued today by the United Nations health agency to combat the pandemic.
The UN World Health Organization (WHO) said the Strategic Advisory Group of Experts (SAGE) on Immunization that advises it on vaccine policy and strategy, recommended further studies in children older than six months and younger than 10 years, since the data are limited.
For pregnant women, SAGE noted that studies in experimental animals using live attenuated or inactivated vaccines found no evidence of direct or indirect harmful effects on fertility, pregnancy, foetal development, birthing or post-natal development.
“Based on these data and the substantially elevated risk for a severe outcome in pregnant women infected with the pandemic virus, SAGE recommended that any licensed vaccine can be used in pregnant women, provided no specific contraindication has been identified by the [national] regulatory authority,” WHO said in its update.
Globally, teenagers and young adults continue to account for the majority of cases, with rates of hospitalization highest in very young children. Between 1 and 10 per cent of patients with clinical illness require hospitalization, and of these from 10 to 25 per cent require admission to an intensive care unit, with from 2 to 9 per cent dying.
Overall, from 7 to 10 per cent of all hospitalized patients are pregnant women in their second or third trimester and they are 10 times more likely to need care in intensive care units than the general population.
Taking note of findings by the United States Centers for Disease Control and Prevention that live attenuated seasonal and live attenuated pandemic vaccines should not be administered simultaneously, the experts said the vaccines could be co-administered provided one or both are inactivated. They found no evidence that such co-administration would increase the risk of adverse events.
The experts found no indication of unusual adverse reactions results from early monitoring of the various pandemic vaccines so far, since those that have occurred are well within the range of seasonal vaccines, which have an excellent safety profile. Although early results are reassuring, monitoring for adverse events should continue.
With regard to the southern hemisphere 2010 winter season, SAGE recommended two options: a trivalent vaccine effective against H1N1, seasonal H3N2 and influenza B, and a bivalent vaccine against H3N2 and influenza B, which might need to be supplemented with a separate monovalent H1N1vaccine.