Reply to Joel Harrison - Offit's calculation was misleading
It is unusual for a correspondent to make so many assertions about another as Joel Harrison has done here about myself [1,2], and a lot of it seems rather speculative and regrettable.
What we do need to address is the issue of multiple vaccines and the use made of Paul Offit's calculation about the number of antigens in vaccine schedule products compared to putative infant capacity  by Offit himself and others. In fact this calculation may be irrelevant to the safety of products or at best only one of many elements involved. In my evidence to the Health and Social Care Committee  I was clear that I was concerned about how this claim was deployed for public consumption. Indeed, this always seems to have been the purpose given that the paper in which it appeared was entitled 'Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System?'  and I gave examples.
For, instance, I quoted from a publication of Offit's own hospital :
"Children have an enormous capacity to respond safely to challenges to the immune system from vaccines," says Dr. Offit. "A baby's body is bombarded with immunologic challenges - from bacteria in food to the dust they breathe. Compared to what they typically encounter and manage during the day, vaccines are literally a drop in the ocean." In fact, Dr. Offit's studies show that in theory, healthy infants could safely get up to 100,000 vaccines at once.”
I cited David Salisbury,at the time British government's vaccine and immunology spokesman, in BBC 2 Newsnight 10 August 2004  :
"The immune system of a baby has got huge spare capacity to deal with challenge. If we didn't, the human race wouldn't survive. But let's look specifically at vaccine. This has been studied carefully. A baby's immune system could actually tolerate perfectly well 1,000 vaccines".
I cited the response of the NHS 'MMR the Facts" team to an enquiry I had made :
"The CMO [Liam Donaldson] is entitled to present his statement about the immune system as a medically established fact rather than theoretical proposition. From the moment of birth a child's immune system is able to cope with the constant barrage of pathogens. As the CMO stated, this is what the..."immune system is designed cope tih (sic)..."As for example, the digestive system is "designed" to digest food and liver is "designed" to detoxify the blood. Part of the licensing process of any combination vaccine, such as MMR, has to show that the combination is safe and effective when administered to the age group for which it is intended. There is recent research from the US which supports this statement as it has specifically looked at the ability of children's immune systems, estimating that a child's immune system could cope with 10,000 vaccines any one time. Please see Offit PA et al (2002) Addressing parents' concerns: Do multiple vaccines overwhelm or weaken infant's immune system? Pediatics, 109 (1): 124-9"
As late as 2015 Elizabeth Miller of Public Health England was talking about "strong arguments against an overload hypothesis" with a citation of Offit's paper .
But the fundamental problem is that it was not I who was making naive use of this possibly irrelevant conjecture but the experts advising the public. I commented (in full) :
"There were several obvious things wrong with Offit’s claim that 10,000 or 100,000 vaccines administered to an infant in one go might be safe. Offit was comparing routine exposure to environmental pathogens, with cocktails of serious disease derived pathogens; it took no account, for example, of the use of adjuvants to boost the antigens and the route of
administration was nothing like routine exposure to pathogens in the environment i.e. in most cases injected when normally we have skin, the digestive system, the lungs which have evolved to protect us..."
For a long time Offit's calculation was used to reassure the public about the safety of multiple vaccines and the expanding schedule, but with so many products on the schedule and so many more in the pipeline there is surely no longer any rational way of regarding this as anything but over-medication [3,8]. This is the present United Kingdom infant vaccine schedule to 12 months:
DTaP, Polio, HiB, HepB+Rotavirus+13 Strain Pneumococcal+MenB (8 weeks)
DTaP, Polio, HiB, HepB+Rotavirus (12 weeks)
DTaP, Polio, HiB,HepB+13 Strain Preumococcal+MenB (16 weeks)
13 Strain Pneumococcal+MMR+HiB, MenC (12 Months)
It is time to stop being gung-ho, and time to start listening to people who report harm.
 Joel A Harrison, 'US county bars unvaccinated children from public spaces amid measles emergency', 7 May 2019, https://www.bmj.com/content/364/bmj.l1481/rr-13
 Joel A Harrison, 'US county bars unvaccinated children from public spaces amid measles emergency', 7 May 2019, https://www.bmj.com/content/364/bmj.l1481/rr-14
 Offit PA, Quarles J, Gerber MA, Hackett CJ, Marcuse EK, Kollman TR, et al. 'Addressing
parents’ concerns: do multiple vaccines overwhelm or weaken the infant's immune system?'
Pediatrics. 2002;109:124–9. doi: 10.1542/peds.109.1.124
 John Stone, 'What David Salisbury said and the DOH’s position on multiple vaccine safety',
BMJ Rapid Responses 20 September 2004, https://www.bmj.com/rapidresponse/2011/10/30/what-david-salisbury-said-a...
 John Stone, 'Irresponsible claims about vaccine safety? Questions for Sir Liam Donaldson and
Prof Lewis Wolpert', BMJ Rapid Responses 3 July 2004, https://www.bmj.com/rapidresponse/2011/10/30/irresponsible-claims-about-...
 Elizabeth Miller, 'Controversies and challenges of vaccination: an interview with Elizabeth Miller', BMC Med. 2015; 13: 267. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608187/
 John Stone, 'Re: How much medicine is too much? And how about vaccines?', 1 March 2019, https://www.bmj.com/content/364/bmj.l902/rr-0
Competing interests: No competing interests