GENEVA, July 13 (Xinhua) -- Countries should first immunize their health-care workers when the A/H1N1 flu vaccines are available in order to keep the integrity of the health system in face of a pandemic, the World Health Organization (WHO) said on Monday.

    "First, health workers should be immunized in all countries in order to maintain a functional health system as the pandemic evolves," Marie-Paule Kieny, director of WHO's Initiative for Vaccine Research, told reporters through a teleconference.

    Kieny said a WHO expert group, which convened last week, had recognized that the spread of the H1N1 influenza is "unstoppable," therefore, "all countries need to have access to vaccines."

    But given the fact that different countries have different epidemiological situations, the countries themselves should make their own decision on vaccination strategies.

    According to Kieny, WHO experts have identified three different objectives that countries could adopt as part of their pandemic vaccination strategy: protect the integrity of the health-care system and the country's critical infrastructure, reduce morbidity and mortality, and reduce transmission of the pandemic virus within communities.

    Although situations are different, all countries should immunize their health-care workers as a first priority to protect the essential health infrastructure, she said.

    As vaccines available initially will not be sufficient, WHO experts also suggest that countries consider a step-wise approach to vaccinate particular groups, notably pregnant women and people with chronic medical conditions, who appear to be at increased risk for severe disease and death from the H1N1 flu infection.

    Children should also be a priority for immunization since they can "amplify" the spread of the disease, especially when they gather in schools, Kieny said.

    According to the official, some drug companies have already produced the H1N1 jabs for clinic trials, but those for real vaccination campaigns would not be available until September or October.

    As most of the production of the seasonal vaccine for the winter in the northern hemisphere is almost complete and is therefore unlikely to affect production of pandemic vaccine, WHO does not consider there is a need to recommend a "switch" from seasonal to pandemic vaccine production, she said.

    WHO would also not change its recommendation for normal vaccination programs against seasonal flu, she added.