Several decades following the vaccine’s introduction, the measles death rate rose, largely because the vaccine made adults, expectant mothers and infants more vulnerable.
This article, by Lawrence Solomon, was first published by the Financial Post
Early in the last century, measles killed millions of people a year. Then, bit by bit in countries of the developed world, the death rate dropped, by the 1960s by 98% or more. In the U.K., it dropped by an astounding 99.96%. And then, the measles vaccine entered the market.
After the vaccine’s introduction, the measles death rate continued to drop into the 1970s. Many scientists credit the continued decline entirely to the vaccine. Other scientists believe the vaccine played a minor role, if that, noting that most infectious diseases similarly petered out during the 20th century, including some, like scarlet fever, for which vaccines were never developed.
The credit for the century-long decline, scientists generally agree, goes to improved nutrition and improved health care, side effects of the West’s growing affluence. In the U.S., the death rate dropped by about 98%, from about 10 per 100,000 population a century ago to one fifth of one person by 1963, the year measles vaccines made their American debut. Both before and after vaccination started, victims tended to be poor.
A study in the American Journal of Public Health, “Measles mortality in the United States 1971-1975,” found the measles death rate to be almost 10 times higher among families whose median income was less than $5,000 than among families whose income exceeded a modest $10,000. Families outside metropolitan areas, who tended to have poor healthcare, had three times the death rate.
An earlier, landmark study in the American Journal of Epidemiology by the Center for Disease Control’s Roger Barkin found similar disturbing results of measles’ toll on the disadvantaged. Here race entered the picture because black children were disproportionately victimized, not by the measles virus per se but by poverty. A poor black child and a poor white child had the same high chance of dying from measles, but because white children rarely lived in abject poverty, measles claimed the blacks.
Measles didn’t only discriminate by income — in another study, Barkin found that children with underlying diseases were particularly vulnerable, and that the “majority of this group were physically or mentally retarded, or both.” The realization that measles was selective in whom it killed led Barkin to emphasize that vulnerable populations, rather than the general population, should be targeted for measles vaccination.
In the pre-vaccine era, when the natural measles virus infected the entire population, measles — “typically a benign childhood illness,” as Clinical Pediatrics described it — was welcomed for providing lifetime immunity, thus avoiding dangerous adult infections. In today’s vaccine era, adults have accounted for one quarter to one half of measles cases; most of them involve pneumonia, one-quarter of them hospitalization.
Also importantly, measles during pregnancies have risen dangerously because expectant mothers no longer have lifetime immunity. Today’s vaccinated expectant mothers are at risk because the measles vaccine wanes with time and because it often fails to protect against measles.
A study in Houston of 12 pregnant women and one who had just given birth, all of whom had measles, found one died, seven suffered pneumonia and seven hepatitis, four went through premature labour and one lost her child in a spontaneous abortion. A study of eight measles pregnancies in Japan found three ended in spontaneous abortions or stillbirths while four babies were born with congenital measles; two mothers endured pneumonia and one hemorrhagic shock. A Los Angeles study of 58 such pregnancies found 21 ended prematurely (three induced abortions, five spontaneous abortions and 13 preterm deliveries); 35 of the 58 mothers were hospitalized, 15 contracted pneumonia, and two died.
The danger extends to babies, whose bodies are too immature to receive measles vaccination before age one, making them entirely dependent on antibodies inherited from their mothers. In their first year out of the womb, infants suffer the highest rate of measles infections and the most lasting harm. Yet vaccinated mothers have little antibody to pass on — only about one-quarter as much as mothers protected by natural measles — leaving infants vulnerable three months after birth, according to a study last year in the Journal of Infectious Diseases. HIV-infected children, who may account for most recent measles-related child deaths, also suffer when their mothers have been vaccinated, since HIV further reduces the antibodies they inherit.
Factors such as these increased the death rate for adults and the very young, helping to reverse the decline in deaths seen in previous decades, according to a 2004 study in the Journal of Infectious Disease, authored by researchers at the Centers for Disease Control and Johns Hopkins Bloomberg School of Public Health.
Vaccines for measles have had spotty safety records. Soon after their introduction, the Vital Statistics of the United States began recording deaths from the measles vaccine, along with deaths from other vaccines. By 1970, one of the two original measles vaccines was withdrawn in Canada and the U.S. after causing atypical measles syndrome, a harsh disease triggering high rates of pneumonia. In 1975, the second original vaccine was withdrawn due to 103-degrees-plus fevers, among other severe side effects. Two variants of this vaccine also proved unsatisfactory. A measles vaccine then became part of the combination MMR (measles, mumps, rubella) vaccine in the 1980s, only to be withdrawn in 1990 by Canada and in 1992 by the manufacturer after reports from Canada, the U.S., Sweden and Japan blamed MMR for febrile convulsions, meningitis, deafness and deaths. A second version of MMR, now in widespread use, is believed safe by government officials.
Safety aside, vaccines repeatedly failed worldwide in the 1980s and 1990s. As described in “Measles Elimination in Canada”, a 2004 report authored by Canadian government officials and academics, “despite virtually 100% documented one-dose coverage in some regions, large outbreaks of measles involving thousands of cases persisted … Clearly, because of primary vaccine failure, Canada’s one-dose program was insufficient.”
The solution finally arrived at — adding a second dose for children — initially seemed to tame measles outbreaks. But in recent years, the new vaccination regime, too, has been failing, with widespread outbreaks again occurring, including among those who have received the recommended dose and especially among infants too young to be vaccinated, and thus unprotected because their mothers had been vaccinated. Now health experts, scrambling to find solutions, are suggesting numerous reforms, including earlier child vaccinations and second doses for adults.
Clearly, the science is not settled, making for parents a numbers game of the decision to vaccinate their children. Some parents rely on the press or health authorities to interpret the numbers. Others defy the authorities and weigh the risks in the numbers differently, in deciding what’s best for their own families. Who are these others? According to a survey in Pediatrics, unvaccinated children in the U.S. have a mother who is at least 30 years old, who has at least one college degree and whose household has an annual income of at least $75,000. In the absence of studies showing vaccinated children to be healthier than those unvaccinated, the parents in these educated households have determined that the numbers argue against vaccination.
Lawrence Solomon is research director of Consumer Policy Institute.
For previous columns in this series on vaccines, see here.