December 13, 2012

IMMUNE MEMORY: Flu’s “first kiss”: Remembered forever.

The study, published Dec. 12 in the peer-reviewed BMC Medicine, looks at all five influenza pandemics of the past 100 years. It finds a variable but often large number of elderly individuals were immune to influenza because their bodies had been infected with a similar virus in the past. In other words, the viruses were recycled.

Reichert says that during the 2009 influenza pandemic, most people over age 62 were immune because the flu virus closely resembled viruses they’d been exposed to before 1947. In 1969, people over age 78 had immunity, the study found. In 1918, it was those over age 45-55 who were best protected.

In Reichert’s view, the “immunity of past experience” has important implications. First, he says in pandemic seasons, flu shots and other resources should be diverted to younger people who aren’t naturally protected and not wasted on the elderly, many of whom will already be immune. Second, he says American businesses should give serious thought to cultivating a cadre of retired, elderly to bring into the workforce in the event of a severe flu pandemic. “If your factory risks being down for a year because so many workers are stricken, the immune elderly could be a tremendous resource,” says Reichert. “Any employer who motivated his retirees could bring them in and only a few would get sick.” He concludes that competitors who prepared this way would have a huge advantage over those who don’t.

I don’t know about that, but perhaps this phenomenon helped to select for longevity in humans. A tribe with even a couple of oldsters who stayed well and could tend to the sick and mind the herds or whatever, would have a huge advantage over one where everyone was sick.