The guidance from the following all state aerosols are a mode for transmission:
UK NICE, UK green book chapter 22 on meningitis, EU Centre for Disease Control.
Until earlier this week, the WHO and NI PHA did too but they conveniently erased mention of aerosols this week.
"Close contact" is not a mode of transmission- the bacteria has to get from one person to another somehow and in this case it could be both aerosols and / or drops of saliva.
In this situation of doubt, best to apply precautionary measures and take airborne mitigations as well. Ventilation, HEPA purifiers, and FFP2 masks that fit snugly.
Ongoing research at Bristol University is also looking at how the bacteria survives on aerosols from human exhalations, here is their July 2025 update:
During the past 12 months, Mia and the team have characterized the aerosol survival of different Neisseria meningitidis strains- serogroups A, B and C – in both artificial and real human saliva. They have found potential mechanisms for what drives death of the aerosolised bacteria in the artificial saliva.
They have identified that real human saliva provides a significant protective effect compared to artificial saliva and prolongs survival, irrespective of relative humidity.
The team have now started to investigate the potential reasons for the protective effect of real saliva. www.meningitisnow.org/meningitis-explained/research/current-research-projects/meningococcal-meningitis-university-of-bristol/