Ministry of Health responds to claims Pfizer vaccine making women's breasts grow by two cup sizes

New Zealand's Ministry of Health has responded to claims the Pfizer vaccine is making women's breasts grow by up to two cups sizes. 

Accounts of enlarged breasts have been circulating on social media from many women who have recently received the Pfizer vaccine, currently being rolled out to Kiwis.  

Some are even referring to it as "the Pfizer boob job". 

"Can confirm the free Pfizer boob job after the first dose," one US woman tweeted.

"I feel like my boobs got bigger because of Pfizer or am I just hallucinating," wrote another.  

In a TikTok video that has racked up over 1.5 million views, user Elle Marshall said she had been an A-cup bra size her "entire life" until receiving the vaccine, which she claims made her breasts grow by "almost two cup sizes". 

So should Kiwi women prepare to make a trip to Farmers or Bendon to buy new bras? 

Not quite. 

A Ministry of Health spokesperson advised Newshub they "have had no reports of breast enlargement in women or men". 

"This is not a known side effect of Comirnaty (COVID-19 Vaccine)." 

According to online science magazine Nautilus, there may be some swelling after receiving the vaccine, but there's a simple explanation. 

"The mRNA vaccines deliver a small amount of genetic code to instruct cells how to replicate the virus' surface protein 'spike', which in turn activates the immune system," a recent article notes. 

"Lymph nodes contain B-cells that use this information to generate antibodies in response to a foreign entity. 

"The buildup of antibodies in the lymph nodes may result in them becoming enlarged. This can lead to breasts feeling larger for a short time following a COVID vaccine, but it is not cause for undue concern."