Whooping Cough News

15th November 2021

Pertussis notifications in England continue at a very low level. The graph below shows weekly cases and is worth comparing with the graph a bit further down the page which was about 1 year previously and demonstrated the enormous drop following the covid lockdown and new mask and social distancing behaviour.

Pertussis cases by week in England 45/2020 to 44/2021

October 17th 2021

I have recently read a scientific paper about working towards a new pertussis vaccine that could be administered in the form of drops in the mouth or nose. What was interesting was the introduction to the paper, that started the same was as most have done for the last 10 years, but with one notable difference that pleased me personally.

They usually start by saying that immunisation has failed to control this disease that is experiencing a resurgence. If you know my work you will know that I believe that most if not all of this “resurgence” is a result of better tests for detecting it. This paper, detailed below, acknowledges that the recent increase in reported cases could be the result of increases reporting or better tools for detecting cases.

This is the first time I have seen this possible explanation for “resurgence” in print, although I could have missed others. Have they heard me? Or does somebody else have evidence like mine? The authors are French, writing in English. Here is the extract:

“The reason for such a resurgence is still a matter of debate and may include better diagnosis of B. pertussis infections due to enhanced surveillance and improved diagnostic tools, strain adaptations, waning of immunity after the introduction of acellular vaccines (aP), and asymptomatic carriage, which favors B. pertussis circulation (Locht, 2016).”

Thibaut Naninck, Vanessa Contreras, Loïc Coutte, Sébastien Langlois, Aurélie Hébert-Ribon, Magali Pelletier, Nathalie Reveneau, Camille Locht, Catherine Chapon, Roger Le Grand,Intranasal inoculation with Bordetella pertussis confers protection without inducing classical whooping cough in baboons,Current Research in Microbial Sciences,Volume 2, 2021, 100072, ISSN 2666-5174, https://doi.org/10.1016/j.crmicr.2021.100072.(https://www.sciencedirect.com/science/article/pii/S2666517421000535)

I await more like this.

April 21st 2021

Pertussis statistics from Public Health England are unique and invaluable. The most recently available figures on laboratory confirmations confirm what we seemed to be seeing from notifications, which are published immediately. Since the Covid-19 lockdown in England on 23/3/20, cases have fallen by over 90%. This exciting observation suggests that there is possible scope for reducing infection by simple hygiene measures such as wearing a mask if we have a cough or cold and avoiding contact with such people in crowded and/or unventilated places.

The chart from PHE which is below has some of my comments added below it. The whole period from 2011 to 2020 represents a curious phase of pertussis recording. In 2012 detection came of age when doctors relatively suddenly became aware that there was a simple blood test for pertussis. Numbers shot up. The four yearly cycling of pertussis predicted 2012 would be a peak anyway but it has not repeated to the same extent in 2016 or 2020. Something peculiar happened in 2012 because infant deaths peaked and pregnancy boosters were introduced later that year with dramatic benefit. The more time passes since 2012 the more it looks like that year was a ‘one off’ and one can only speculate on a cause. My personal hunch is that an unknown factor is operating that affects transmission or manifestation, independently of prevalence and immunisation; one of the famous unknown unknowns.

The current low incidence worries me slightly because it is telling us there is not much about. Good news you might think, but we now know we maintain lifelong immunity by being constantly and frequently exposed to pertussis which boosts immunity without causing symptoms. If that is not happening it might mean that eventually there will be a catch up of symptomatic cases.

histogram of pertussis by quarter 2011 2020 from Public Health England with comments
Data from Public Health England

Whooping cough news items

12th November 2020

The graph above is rather startling. It starts a year ago in November 2019 when notifications were about 100 per week, somewhat more than the same time in 2018, but in line with the 4 yearly cycling of whooping cough which was expected to peak in the last quarter of 2020.

Lockdown in the UK started in week 13, 2020. The graph shows a sharp fall beginning in week 12. If the figures a true reflection of incidence then it suggests people must have been taking anti infection precautions before the lockdown came into effect as one would expect at least a 3 week lag between infection and diagnosis.

Many other infectious diseases have shown similar falls. How much is true reduction and how much is missed diagnosis or notification is open to debate, but it is exceedingly interesting.

9th August 2020

The Covid-19 lockdown appears to have affected whooping cough transmission if the statistics are to be believed. There is vastly less whooping cough compared with March and April when the lockdown policies were being implemented in most countries. At that time in the UK notifications were running at about 50 to 100 per week; fairly usual one would say.

Over the last month or two, notifications have dropped to about five per week. This is a remarkable drop and it is unlikely to to be explained by patients and medics being distracted by Covid, although that might play a small part.

It is most likely that isolation from other people, as required in lockdown breaks the transmission. This is not surprising given what we know about how it is transmitted (probably very similarly to Covid-19). The magnitude of the change is remarkable and will probably change the way we regard transmissible infections in the future. I am thinking principally about our ‘carry on regardless, and not wearing masks’ behaviour, which has been part of our cultural norm in Europe.

3rd July 2020

2020 is to be the expected peak in the 4 yearly cycles in the UK (and in some other countries too).

The first half of 2020 started with indications that the numbers were slightly up in 2019 consistent with expectations.  Numbers from about April however dropped by about 80%.

There are two possible explanations. Firstly, it could be that the demands of covid-19 management have distracted from other diseases. Secondly it could be that the social distancing and disinfection required for covid-19 control has interrupted pertussis transmission concomitantly.