A reader asked an offline question that is general enough to post about (NB : I try to respond to as many questions as I can, but I’m traveling and can’t keep up, so in most cases I won’t be able to respond. I also don’t hand out personal medical advice over the internet, something I consider bad practice). CDC says on the basis of clinical trials with the unadjuvanted vaccine used in the US that two shots, 21 days apart, are needed for children under 10. WHO, on the other hand, is telling its member nations that one will suffice. Why the confusion ?
We may be comparing apples and oranges. Many countries use adjuvants in their vaccines which promote a quicker and more powerful response. It appears that a single dose is sufficient for children under 10 when there is adjuvant in the vaccine. Canada currently is using adjuvant, as are many other countries, although concerns from parents have forced the Canadians to offer an adjuvant-free option. Helen Branswell has an excellent piece with a Q&A on the controversy that you should read in its entirety, but it is pitched to a Canadian audience, so I’ve take out some of what I consider the more general points :
Based on GSK’s [vaccine maker GlaxoSmithKline] early data, Canadian officials say it’s possible kids in Canada will only need one dose, but they want more information before making that decision.But given that there must be a 21-day interval between the doses, there is still time to figure this out, experts say.
"For me, given the level of activity, the second wave activity already occurring, our goal should be ... get a first dose into kids. Then we can discuss the second dose," said Dr. Danuta Skowronski, a flu expert with the British Columbia Centre for Disease Control.
"We still have time to work out whether that second dose will be necessary."
[snip]
A spokesperson for the Public Health Agency of Canada noted that parents who want to go [the route of demanding an unadjuvanted vaccine] need to realize kids will need two adult-sized shots of vaccine, given 21 days apart. And the full protection of those shots will only really be in effect two or three weeks after the second shot is given.
[snip]
"My concern is we are having intense second wave activity now. So for parents to be holding out for an unadjuvanted when we’re facing intense activity now, they’ll miss the boat in terms of protecting their kids," said Dr. Danuta Skowronski, a flu expert with the British Columbia Centre for Disease Control.
"Better the bird in the hand than two in the bush."
[Dr. Joanne Langley, who is chair of the Canadian National Advisory Committee on Immunization], a pediatrician who specializes in infectious diseases, agrees.
"I think as a pediatrician, knowing these children are vulnerable, knowing that the likelihood of them having a strong and quick immune response ... is so much lower with an unadjuvanted preparation . . . I think the best choice in that circumstance is to go with an adjuvanted preparation."(Helen Branswell, Canadian Press)
So that’s point one. Every child is in a race with the virus. My 5 year old grandson lost the race and is now suffering through fever, aches, pains and feeling ill from Tamiflu. He has asthma so Relenza is not an option. A couple of weeks more and he would have gotten some protection into him. But the virus got there first.
Or maybe more than a couple of weeks. In the US there is no option to get adjuvanted vaccine if you want your child to be protected faster. Again from Helen Branswell :
U.S. pandemic planners decided against using adjuvant in their vaccine. And vaccine without adjuvant doesn’t induce a terrific immune response in little kids, whose immune systems are still developing and who haven’t had as much exposure to flu viruses as older children and adults.The study results released Monday were based on a trial in 583 children aged six months to nine years of age who were given two doses of H1N1 vaccine without adjuvant at a 21-day interval.
The response to one dose was poor in children six months to 35 months - only 25 per cent reached the protective mark. In children three to nine years, the rate was 55 per cent, still too low by regulatory standards.
But Dr. Anthony Fauci, head of the NIAID, said after the second dose 100 per cent of the younger children and 94 per cent of the older children had antibody levels that suggest they are protected against the virus.
With an adjuvanted vaccine, a half dose gives antibody titers thought to provide protection in a single shot in babies 6 months to a year and a half. This is the highest risk age group in the population. But adjuvanted or not adjuvanted, it is likely that one shot is better than none at all. That seems to be WHO’s reason for recommending one dose for children under 10. There’s a global shortage of vaccine and their objective is to get some protection to as many children as possible. Yesterday we noted the melancholy data on child death from pneumonia. Well over half of these deaths are vaccine preventable. With an influenza pandemic ramping up in the developing world, WHO is trying to stem the tide of child deaths that inevitably will follow in its wake.
There are lots of agonizing decisions to be made and no sure answers. Influenza virus is a wily adversary. It’s like playing timed chess with a grand master without knowing all the moves or the rules. But move within a certain period of time we must. Is the move the right one ? We’ll find out after the game is over.
