To not want baby near unvaccinated toddler?

[victoriaspomge]

So basically my partner wants his half brother's (same dad) younger half brother (same mum) to come and meet our baby.
He has a daughter who is 2 years old who he says is our kids cousin.

My partner is no relation to him or his daughter biologically but because they share a half brother he feels as if it's his brother as well and that they are family.

He dosent really know him and doesn't have his number and has only met him in the last 10 years.

They only hang out if it's with their mutual half brother.

I know the 'brother' is very anti vax and has not got his 2 year old vaccinated despite living in a city where it has had a lot of cases of measles.

Baby is too young to be have the MMR and I am extremely worried about my baby meeting this 2 year old.

AIBU to feel like this?

The advice I got when my kid was exposed to measles before she received the MMR ( she was too young before anyone asks) was that the reason they delay MMR to 13 months is because the infant retains the mother's immunity until that time and the immunisation needs a system to be "clear" of measles in order for the immune response to generate. So it would depend on the age of the child. Breastfeeding also has huge protections too.

his half brother's (same dad) younger half brother (same mum)

You lost me here. Is this some sort of sex commune with all these loosely related people?

As someone whose newborn baby caught whooping cough (pre maternal vaccination) I would say YANBU. I never discovered who passed it to ds largely because our GP didn't recognise ds had whooping cough. I had to demand he was swabbed so it was highly likely that if another child was taken there they wouldn't have been swabbed either. My older ones had been vaccinated and didn't pick it up from the baby but it was a hugely difficult time soon after birth.

Your older children could still have passed it to the baby? Being vaccinated doesn't mean it absolutely wasn't them.

Well they had no symptoms either so very unlikely to have been them. GP asked if siblings were unwell so as to give antibiotics to them as well but they were fine. I imagine baby caught it on the school and nursery run or at parents’ assembly.

That sounds like an incredibly difficult time.
Whooping cough is an interesting one. Vaccine induced immunity wanes very quickly - from around 4 years post vaccine. Most of the adult population will not be covered by vaccine induced immunity but may have immunity from catching the infection. Natural immunity is longer lasting.
It is under diagnosed as adults don't tend to get the 'whoop' and from your experience, it sounds like it is also under diagnosed because of a reluctance to swab for it.
It calls into question how seriously health professionals take it.

Tbh I only knew it was whooping cough because I was old enough to remember the public information advert of the seventies/ eighties largely because my youngest sister was hospitalised with whooping cough as a baby herself. GP didn't believe it was whooping cough because there were no recorded cases in the area at that time. There were likely no recorded cases because of a reluctance to swab.

In partnership with NHS

For parents with very young babies who are too young to be vaccinated, the risk of exposure to vaccine-preventable diseases like measles or whooping cough from unvaccinated toddlers in everyday settings is generally low but not zero. It depends on several factors:

1. Community vaccination coverage

• In areas where most children are vaccinated, outbreaks are rare, so exposure risk in everyday settings (parks, playdates, daycare) is low.
• In communities with lower vaccination rates, the risk increases because unvaccinated toddlers are more likely to carry and transmit these diseases.

2. Type of disease

• Measles is extremely contagious and can linger in the air for up to 2 hours after an infected person leaves a room. Exposure can happen even briefly in indoor settings.
• Whooping cough (pertussis) spreads through close respiratory contact. Young babies are particularly vulnerable, and infection can be severe.
• RSV is highly contagious but usually causes milder illness in older children; the risk is mainly that older toddlers may transmit it to babies who can get more serious symptoms.

3. Everyday interactions

• Casual outdoor contact, like passing in a park, is very low risk.
• Indoor settings where unvaccinated toddlers are in close proximity to babies (daycare, playgroups, crowded waiting rooms) pose a higher risk.

4. Protective measures

• Ensuring everyone around the baby is vaccinated (parents, siblings, carers) is the most effective protection. Adults can safely have the measles, mumps and rubella (MMR) vaccine if they are unsure of their status or have only had one dose
• Hand hygiene, limiting contact with anyone who is unwell, and avoiding crowded indoor settings during outbreaks further reduce risk.
• Breastfeeding provides some temporary antibodies, giving partial protection.

Most everyday interactions carry low risk, especially when family and community vaccination coverage is high. The highest risk comes from prolonged indoor contact with unvaccinated or unwell children. Being aware, practicing sensible hygiene, and keeping close contacts up to date with vaccines can substantially reduce this risk.

For further information, you could have a look at some of the following:

• Why vaccination is important and the safest way to protect yourself - NHS
• MMR vaccination leaflet
• A guide to the MMRV vaccination
• Measles: it's not just a kids' problem and it can be serious