Posted by: Chris Maloney | May 20, 2013

Britain’s Measles Outbreak: Are Health Care Workers Or Unvaccinated To Blame?

Reported cases of measles in England and Wales...

Reported cases of measles in England and Wales from 1940–2007. The graph shows the bi-annual cycle of epidemics that followed the war. (Photo credit: Wikipedia)

Only one third of health care workers in Britain have been asked if they are immune to measles before taking jobs to care for the ill.

So a recent study has called for a change: “To achieve complete immunity, it is cost-effective to screen and then offer immunization.” So how many of these workers were not immune to the measles? Oh, 3.3%. (Abstract at bottom of page)

That’s well above any standard for herd immunity, which varies between 80-90%. The concept of achieving complete immunity flies directly in the face of the reality that some individuals will simply not develop immunity despite multiple vaccinations. How many? Probably about 3.3%. The U.S. immunity has been estimated at 93%, and we have the compulsory vaccinations that Britain is considering.
The recent articles point to an epidemic of measles in Britain based on very low vaccination rates. Not for the children now, who are receiving vaccinations at U.S. rates, but for those in a certain time period when vaccination levels dropped in response to reports of links between measles vaccination and autism. British families do not see the sort of death rate from childhood diseases seen in low-income countries: “Children without a (vaccination) card at enrolment had a significant threefold higher mortality over the 2-year follow-up period than those fully vaccinated.”  If that was the case, then we wouldn’t be talking about vaccination at all. But the discussion has moved in higher income countries from saving lives to whether universal vaccination will achieve eradication and whether that goal supersedes parents’ choice.
Clearly the evidence does not support the idea that complete eradication of these illnesses is possible. If the U.S. levels are at 93%, then we have certainly achieved herd immunity status. But there are still measles outbreaks in the U.S. every year.

Whenever the outbreaks are among unvaccinated or primarily unvaccinated children, then the news covers the story extensively. But if the outbreak occurs among vaccinated children, the story does not get the same coverage. When an outbreak of measles occurs in a vaccinated population, the researchers will often redefine vaccination as receiving the maximum number of shots rather than just one.  Or they will point out that vaccination received outside the country is just not as good as a vaccine received locally.  The issue is not defined to measles. Whenever a vaccine is shown to be ineffective, the answer is not to question the vaccine, but to double the dosage. Witness the Maine change in vaccine requirements with the widespread outbreak of mumps nationwide in vaccinated college students.  Or the history of continued chicken pox in a highly vaccinated school.
While the most recent outbreak in Britain is getting press, there have been periodic outbreaks over time. Rather than getting our news from the newswire, it’s better to look at recent reports from Britain that have been fully analyzed by the experts. Here’s the report from Britain on a large outbreak from Jan-June of 2012: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20226

It notes that 92% of those eligible are getting vaccinated. So the parents are vaccinating now, we’re just going to keep claiming the current outbreak is because they weren’t vaccinating before, and all those children are affected.
In the last British epidemic, which  was last year at this time, how many cases were really the measles? Of 1,339 cases, 359 were confirmed as measles. Almost 40% were definitely not measles.

But those cases that were the measles were definitely all in the unvaccinated crowd, yes? It’s a bit more complicated than that: “Of the 359 confirmed cases, …84 (23%) were under one year of age and too young to be vaccinated and 106 (30%) were 15-years-old or older….Most confirmed cases eligible for vaccination, i.e. >12 months old, were not fully vaccinated (38% had no previous MMR vaccination, 16% had only one dose of MMR) and information was not available for 68 (19%) cases (Figure 2). Twelve of the confirmed cases had been vaccinated with two doses of MMR vaccine.”

So I’m a bit confused. The report says most of those older than 12 months were not full vaccinated, and then includes those that got one vaccine in with the 38% who were unvaccinated. If we reverse it, then most of those getting measles were at least partially vaccinated. Overall, we’re talking about initial reports of 1,339 cases, of which 359 definitely had the disease, and of those 68 were not eligible for vaccination. Those who definitely had not been vaccinated were 38%, or 111 people. So the epidemic of 1,339 people results more from doctors over-reporting (40%) than on actual cases (27%) and is blamed on 111 (8%) unvaccinated individuals.

Perhaps a better title for the news reports would be “Britain continues to get false reports of epidemics of the measles despite wide-spread vaccination.” But that wouldn’t sell papers.
The discussion of those who refuse vaccination is rife with judgments. A U.K. discussion of an outbreak in 2008 said “the primary case was probably an 8-year-old unvaccinated travelling child.” Evidently the “travelling community” is causing the spread of public disease. It’s best to lock your doors and move them along as quickly as possible. Vaccination needs to be treated as the complex issue it is for countries where it is no longer a life-or-death easy decision. It does not need to be used as a tool for class warfare or to terrorize a populace with tales of epidemics that are more over-reporting than substance.
Occup Med (Lond). 2003 Sep;53(6):398-402.

Prevalence of measles susceptibility among health care workers in a UK hospital. Does the UK need to introduce a measles policy for its health care workers?

Ziegler E, Roth C, Wreghitt T.

Source

Communicable Disease Surveillance Centre, 61 Colindale Avenue, London NW9 5EQ, UK. emma.ziegler@suht.swest.nhs.uk

Abstract

OBJECTIVES:

First, to determine the prevalence of measles non-immunity in a group of health care workers (HCW), and secondly, to investigate what pre-employment screening for measles is carried out by NHS occupational health departments.

METHODS:

Two hundred and eighteen HCWs with patient contact on the medical wards at Addenbrooke’s hospital provided an oral fluid sample and answered a questionnaire. A postal survey of Association of National Health Occupational Physicians Society (ANHOPS) members was conducted to assess whether UK NHS Trusts identify measles non-immune individuals.

RESULTS:

Of the HCWs tested, 3.3% of were found to be non-immune to measles (both oral fluid and confirmatory serum sample were measles IgG negative). Less than one third of a sample of 80 NHS occupational health departments enquired about measles immunity.

CONCLUSION:

The prevalence of measles non-immune health care workers is low, but with a fall in uptake of MMR immunization and increased likelihood of measles outbreaks, it is important to identify these at-risk individuals. Serum testing is the most reliable method to use. Oral fluid testing and history of measles disease or vaccination are unreliable methods of identifying non-immune individuals. To achieve complete immunity, it is cost-effective to screen and then offer immunization. NHS trusts vary greatly in their measles policies for health care workers.

PMID: 14514907
J Infect Dis. 2004 May 1;189 Suppl 1:S91-7.

Population immunity to measles in the United States, 1999.

Hutchins SS, Bellini WJ, Coronado V, Jiles R, Wooten K, Deladisma A.

Source

National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. ssh1@cdc.gov.

Abstract

To estimate population immunity, we examined measles immunity among residents of the United States in 1999 from serological and vaccine coverage surveys. For persons aged >or=20 years, serological data from the third National Health and Nutrition Examination Survey (1988-1994) were used. For persons or=12 years of age and 99% vaccine efficacy was used for those with failure of a first dose who were revaccinated. Overall, calculated population immunity was found to be 93%. Although there was not much variation in immunity by region and state, in some large urban centers immunity among preschool-aged children was as low as 86%. Overall, geographic- and age-specific estimates of a high population immunity support the epidemiological evidence that measles disease is no longer endemic in the United States.

PMID: 15106096
Epidemiol Infect. 2012 Nov 9:1-8. [Epub ahead of print]

Outbreak of measles in Central and Eastern Cheshire, UK, October 2008-February 2009.

Ghebrehewet S, Hayhurst G, Keenan A, Moore H.

Source

Cheshire and Mersey Health Protection Unit, Liverpool, UK.

Abstract

SUMMARY We describe the largest outbreak of measles in Central and Eastern Cheshire (North West England) since the MMR vaccine was introduced in 1988, the majority of cases were not vaccinated and more than 20% of the cases belonged to the travelling community. Over 4 months, 147 clinical cases of measles were notified locally to the Cheshire & Merseyside Health Protection Unit (CMHPU). Of these, 67 (45•6%) were laboratory confirmed, 42 (28•6%) were negative, and one was equivocal, leaving 23 probable and 14 possible cases. The primary case was probably an 8-year-old unvaccinated travelling child, symptomatic on 1 October 2008. Measles spread locally and within school-aged children until early February 2009. Most of Central and Eastern Cheshire, including 23 educational institutions (playgroups, nurseries, primary schools, secondary schools, colleges), were affected, showing that there were enough susceptible/unvaccinated children to sustain an outbreak. Nearly a quarter of the confirmed cases (15/67, 22•4%) were aged

PMID: 23137521

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