A letter from Philip Mortimer of the UK’s Health Protection Agency to the CDC journal, Emerging Infectious Diseases, calls attention to an apparent increased risk for death from influenza among a subpopulation, pregnant women. Mortimer alerts us to the fact that most (all?) national contingency plans for pandemics do not take this into account.
Mortimer cites literature from the 1918 pandemic that contains ominous figures:
Bland reported on pregnant influenza patients in Philadelphia and elsewhere in the fall of 1918; of 337, 155 died [Bland PB. Influenza in its relation to pregnancy and labour. Am J Obstet Dis Women Child. 1919;79:184-97]. Harris obtained by questionnaire from obstetricians medical histories of 1,350 pregnant patients in Maryland and in 4 large US cities [Harris JW. Influenza occurring in pregnant women: a statistical study of thirteen hundred and fifty cases. JAMA. 1919;2:978-80]. Pneumonia developed in half (678) of these patients and 365 died. Death rates from pneumonia were >40% for every month of pregnancy; fetal loss was >40% in all months but the fifth (37%).
According to a contemporaneous report from England, the influenza death rate for pregnant women was 25.4% [Bland PB. Influenza in its relation to pregnancy and labour. Am J Obstet Dis Women Child. 1919;79:184-97]. These inquiries into pregnancy must have been biased toward severe cases, but the influenza pandemic in 1918-19 may nevertheless have decreased live births in England and Wales, which reached new lows in the first half of 1919 [Registrar General’s Report 1918/19. London: Her Majesty’s Stationery Office; 1919. p. xxviii]. A controlled American study during 1975-1979 has since confirmed that pregnant women are at risk for influenza even in interpandemic years [Mullooly JP, Barker WH, Nolan TF. Risk of acute respiratory disease among pregnant women during influenza A epidemic. Public Health Rep. 1986;101:205-11]. (P. Mortimer, letter in Emerging Infectious Diseases, Open Access)
A characteristic of pandemic years compared to interpandemic years is a marked shift of the age distribution of cases to younger age groups, particularly young adults. We also know that pregnant women have altered immune systems.
So Mortimer makes a good point. Will it be lost on policy makers?