Old meningitis B vaccine ‘may also protect against gonorrhoea’

Tuesday July 11 2017

Complications of gonorrhoea include infertility in women

Gonorrhoea and meningitis B have genetic similarities

“Meningitis vaccine may also cut risk of ‘untreatable’
gonorrhoea, study says,” is the headline in The Guardian.

The news comes from the results of a study in New Zealand that
found people who’d been given an old version of the meningitis
B vaccine were less likely to be diagnosed with gonorrhoea.

But no protective effect was found for chlamydia,
which is often diagnosed at the same time as gonorrhoea.

The publication of the study is timely – just last week the
World Health Organization issued
a warning
about the rise in antibiotic-resistant strains of
gonorrhoea.

The researchers claim this is the first vaccine to show any
protective effect against gonorrhoea, but the vaccine in
question is no longer in use.

variant
of the vaccine
is currently given to babies in the UK as
part of the routine NHS vaccination schedule. As the New
Scientist magazine speculates, if the biological mechanism is
discovered, we may see a sudden drop in gonorrhoea cases in 20
years’ time.

But it’s unlikely that a dedicated vaccine against gonorrhoea
will be available for at least a few years. And that prospect
is not a certainty by any means.

For now, the most effective way to prevent gonorrhoea is to
always use a condom
during sex, including oral and anal sex.

Where did the story come from?

The study was carried out by researchers from Sexual Health
Services, Waikato District Health Board, and the University of
Auckland in New Zealand, and Cincinnati Children’s Hospital in
the US.

The research was funded by GSK Vaccines, a pharmaceutical
company, and Auckland UniServices, a branch of the university
that partners academics with industry. No conflicts of interest
were declared.

The study was published in the peer-reviewed
journal The Lancet.

The UK media’s reporting was generally accurate – but the
headlines weren’t.

The Guardian’s headline talks about “untreatable” gonorrhoea,
but the study didn’t look at whether any of the people had
drug-resistant gonorrhoea or not. The research looked at data
captured between 2004 and 2016, when drug-resistant gonorrhoea
was less of a concern.

The Independent’s headline – “World first as scientists develop
vaccine that reduces chance of catching gonorrhoea” – is also
inaccurate. The vaccine in question already existed, and it
hasn’t definitely been proven to reduce the chances of catching
gonorrhoea.

What kind of research was this?

This case-control
study
 looked at people with a gonorrhoea diagnosis and
whether or not they’d had a meningitis vaccination in the past
to see if there was an association. 

Gonorrhoea is a sexually transmitted infection caused by
Neisseria gonorrhoeae bacteria, and is associated with multiple
issues, including pelvic inflammatory disease, infertility and
chronic pain.

Antimicrobial resistance has increased in recent years, and
some strains of the infection are now resistant to drugs.

Researchers previously noted a decline in gonorrhoea diagnoses
in New Zealand after a mass vaccination programme for
meningococcal B, a serious cause of life-threatening infections
such as meningitis and blood poisoning.

Meningitis B is caused by Neisseria meningitides, a bacteria
similar to the one that causes gonorrhoea, so experts thought
the MeNZB vaccine may be able to protect against both.

This type of research is useful for looking at a large
population of people and examining trends and associations –
but it can only show a link, not prove cause and effect.

randomised
controlled trial
would be needed to do this, where the
vaccine is offered to some people and not others, but this
would be unethical.

What did the research involve?

Researchers looked at 14,730 people aged between 15 and 30 who
received a positive diagnosis of gonorrhoea or chlamydia at a
sexual health clinic between 2004 and 2016.

They wanted to see if having the meningococcal B vaccine
decreased the risk of getting gonorrhoea.

Of those involved, 1,241 people had a gonorrhoea-only
diagnosis. Chlamydia-only diagnoses were used as the control
group, which included 12,487 people.

Coinfection with both gonorrhoea and chlamydia is
relatively common in sexually active adults who don’t use
condoms.

This means someone being diagnosed with chlamydia but not
gonorrhoea could be the result of the meningococcal B vaccine.

Further analysis was done to include the 1,002 people who had
both infections.

The researchers looked back over records from the New Zealand
National Immunisation Register to identify which participants
had received the MeNZB vaccine between 2004 and 2006.

They were able to link people diagnosed with gonorrhoea or
chlamydia to their vaccine history through unique National
Health Index numbers. They then adjusted the results for
ethnicity, deprivation levels, geographical area and sex.

What were the basic results?

The researchers found 41% of the participants diagnosed with
gonorrhoea only had been vaccinated against meningitis B,
compared with 51% of the chlamydia-only group.

They also found:

  • People who had been vaccinated were 31% less likely to have
    a gonorrhoea diagnosis than a chlamydia diagnosis (adjusted
    odds ratio [aOR] 0.69, 95% confidence
    interval [CI]
    0.61 to 0.79).
  • The effect of vaccination appeared to decrease over time.
    Subgroup analyses found the effectiveness of the vaccine was
    20% in the period immediately after the vaccination programme
    from 2004-09 (95% CI 2% to 34%) compared with 9% from 2010-14
    (95% CI 0% to 25%).
  • When people with coinfection were included in the
    gonorrhoea group, the effectiveness of the vaccine reduced to
    23% (95% CI 15 to 30).

How did the researchers interpret the results?

The authors concluded that, “Exposure to [the] MeNZB [vaccine]
was associated with reduced rates of gonorrhoea diagnosis – the
first time a vaccine has shown any protection against
gonorrhoea.

“These results provide a proof of principle that can inform
prospective vaccine development not only for gonorrhoea but
also for meningococcal vaccines.” 

Conclusion

This large study found an association between having the MeNZB
vaccine and a reduced likelihood of being diagnosed with
gonorrhoea.

But it’s difficult to form any firm conclusions because of the
nature of the case and control groups.

For example, given that both groups were sexually active, we
don’t know why the majority of people with gonorrhoea didn’t
also have a chlamydia infection, and how this may have affected
the results.

It could just be down to pure chance and have nothing to do
with the vaccine.

So before we celebrate the alleged “cure of gonorrhoea”, there
are many things to consider:

  • The vaccine in question is no longer in use as a vaccine
    against meningococcal B. The Men4C jab is now used in the UK.
    Though it does have many similar components, we don’t know if
    these are useful in protecting against gonorrhoea. Research now
    needs to focus on whether the association still exists with the
    new jab.
  • Although the authors adjusted for some variables, other
    factors might be at play that may have affected the results,
    such as people’s education, diet, and immune system strength.
  • No new vaccine has actually been developed. The indication
    that something in the MeNZB vaccine might increase protection
    against gonorrhoea requires further research to pinpoint how it
    does so.
  • The research was only conducted on people who were
    diagnosed at a sexual health clinic, and didn’t include data
    from GP surgeries. Many cases in the community could have been
    missed, and these people could have different immunisation
    trends.
  • We don’t know how long the potential protective effect
    lasts for, as it seemed to decrease over time.

It’s very much a case of “if” rather than “when” a gonorrhoea
vaccine is developed. For now, the best way to protect yourself
against gonorrhoea, chlamydia and other STIs is to always use a
condom during vaginal, oral and anal sex.

Read more about how to have
safe sex
.

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