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New TB vaccine most effective when not co-administered with other childhood vaccines

Ota M. Sci Transl Med. 2011; [Published online ahead of print June 22, 2011].

A new tuberculosis vaccine given to infants is most effective when administered alone, according to new findings released online this week.

The new TB vaccine (MVA85A, Oxford-Emergent Tuberculosis Consortium) showed promising results among West African infants when administered alone vs. co-administration with other routine childhood immunizations. The findings could overhaul the way routine childhood vaccines in developing countries are administered, according to a press release.

The bacillus Calmette-Guérin (BCG) vaccine is given at birth in developing countries, in accordance with WHO recommendations. Although the BCG vaccine protects against severe forms of childhood TB, the increasing prevalence of TB in adults indicates that this effect is not long-lasting, and a vaccine with longer-lasting protection is needed. However, the researchers said because of its ability to boost immune responses to hepatitis B and oral polio vaccines, it makes sense to develop a vaccination strategy against TB that includes the BCG vaccine.

MVA85A is a new TB vaccine that is designed to enhance the BCG vaccine. Martin M. O. Ota, MD, and colleagues tested whether MVA85A could be given at the same time as the other childhood vaccines. The researchers looked at three groups of 4-month-old infants: The first group received the normal regimen of childhood vaccines; the second group received the normal regimen of childhood vaccines plus the BCG vaccine and MVA85A; and the third group received the MVA85A vaccine alone.

The team recorded a significant immune response in the second and third groups, but infants’ immune response to MVA85A was significantly lower when given with routine childhood vaccines (it remains unclear why this is case), according to the release. The results indicate that the MVA85A and BCG vaccines may work best when given together, but at a separate time from other childhood vaccines.

The data raise the possibility that standard childhood vaccine schedules may need revision to incorporate a new generation of vaccines against TB, the researchers concluded.

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