Sometimes good things happen when you least expect them…remember all of the hoopla over the 1976 vaccination program for the pandemic that never happened? Turns out now that people who got immunized against the 1976 “swine flu” epidemic that never materialized may have benefited from the shots after all — they may have been protected from the 2009 H1N1 swine flu strain. Tests of blood from medical staff and their spouses showed those who had been vaccinated in 1976 had evidence of extra immune protection against both the 2009 H1N1 swine flu and the seasonal strain of H1N1 that circulated the year before.
The study supports a theory that different strains of flu virus cycle in and out of circulation and that getting a flu vaccine every year may protect people from as-yet unseen flu strains in the future. Every year, several different strains of influenza circulate. The viruses are mutation-prone and change a little bit every year, forcing vaccine-makers to reformulate the seasonal flu vaccine cocktail every year too.
Several times a century, a new strain pops up and causes a pandemic. That happened in 1918 with H1N1, 1957 with H2N2 and 1968 with H3N2. Usually, the new pandemic strain settles down and joins the seasonal mix, which may eventually happen with the 2009 H1N1 strain. In 1976, a new strain of H1N1 broke out at an Army base in New Jersey and U.S. officials, worried about a pandemic, rushed out a vaccine and pushed hard to vaccinate the population.
The 1976 virus was a distant cousin of the 1918 pandemic H1N1 and of the current swine flu pandemic strain. Before the 2009 swine flu reached Tennessee, McCullers and colleagues tested the blood of 116 St. Jude employees and their spouses who were 55 and older, including 46 people vaccinated in 1976.
It was not possible to follow the employees and find out if they were less likely to catch the 2009 H1N1 swine flu if they had been vaccinated in 1976, because all were vaccinated against the 2009 virus as soon as a vaccine was available. But tests of their blood indicated they were protected.
This study points out two lessons:
- It appears that the 1976 vaccine had a benefit and “wasn’t as bad as everyone thought”.
- Health officials need to re-think about how vaccine effectiveness is measured.
It is not considered ethical to vaccinate people and then expose them to an infection, so therefore researchers usually just measure whether a vaccine makes the body produce antibodies. But 97 percent of the St. Jude medical staff produced antibodies against the 2009 H1N1 virus. For most, researchers discovered that these antibodies were not terribly functional. Only the people who had received the 1976 vaccine had antibodies that actually neutralized the 2009 virus.