This is the graph the government show as evidence that the vaccine does prevent whooping cough.
It shows that ‘notifications’ of whooping cough (the dark blue line) had fallen dramatically during the 1960s, but rose again during the late 1970s and early 1980s when the immunisation rate (the pink line) fell. Notifications are voluntary reports of cases of whooping cough made by GPs and hospitals to the Department of Health (DoH). They are notoriously unreliable. Under reporting is common. It is known that the majority of reports can be made by a small number of GPs. Most importantly, reporting relies on the correct diagnosis being made by the doctor. Whooping cough is difficult to diagnose, as there are many other causes of a bad cough. Doctors are more likely to have diagnosed whooping cough during the widely publicised epidemics of the late 1970s and early 1980s.1They are also more likely to diagnose an illness in an unvaccinated child, assuming, not necessarily correctly, that a vaccinated child is protected.
The media coverage during the 1970s and 1980s certainly put whooping cough onto the front pages. The DoH was repeatedly warning GPs that epidemics of whooping cough were imminent. These warnings became self-fulfilling prophecies as GPs suspected that most children with a prolonged cough must have whooping cough. Also, GPs were more likely to diagnose a prolonged cough as whooping cough in an unvaccinated child compared to a vaccinated child. Their assumption that the vaccine worked led to evidence, based on reported cases, that it did work. The two epidemics seen in the graph occurring either side of 1980 (orange arrow on the graph above) were, in fact, expected as part of a roughly 4 yearly cycle of epidemics; each epidemic is represented on the graph by a peak in the blue line. It certainly appears from the notification figures that they were the largest epidemics for 30 years, but could this just be due to over-reporting by GPs, assuming most coughs were whooping cough? An editorial in the British Medical Journal admits, “surveillance is so incomplete that enhanced awareness…can result in apparent epidemics”.