“Big Pharma” stocks took a tumble this morning following the news that President-elect Donald Trump has appointed Robert F. Kennedy Jr as US health secretary in his upcoming administration.GSK PLC and AstraZeneca PLC came under pressure as alarmed investors reacted to the news of the vaccine sceptic’s potential influential role.Globally, pharmaceutical companies reacted negatively to the news with Germany’s Roche and Demark’s Novo Nordisk slipping.Furthermore, Moderna Inc and Pfizer stock are also looking to open lower in pre-market trading before trading begins on Wall Street.On Thursday afternoon, Pfizer experienced a drop of around 57 cent, while Moderna stock saw a dip of $2.64 in its price.Notably, both companies were involved in the developments of Covid-19 vaccines which Kennedy has criticised the rollout off.Do you have a money story you’d like to share? Get in touch by emailing money@gbnews.uk.Kennedy is a known “vaccine sceptic” who is likely to be Trump’s new health sec GETTY / PA Health professionals have slammed Kennedy over his various stances when it comes to public health. In his role, the ex-Democrat will lead the Department of Health and Human Services, which regulates vaccines.He has previously pledged to rein in pharmaceutical companies and regulators as part of his efforts to “Make America Healthy Again”. His appointment is subject to Senate approval which is set to have a Republican majority.In recent years, Kennedy has hit back at public mandates for vaccines and has asserted the Trump administration will ban flouride from public water supplies, which is used to strengthen teeth.Following the election, he asserted he has no plan for a sweeping ban of vaccines. However, a Trump White House could change the rules as to which vaccines are recommended to insurers which would impact access.Russ Mould, an investment director at AJ Bell, warned that drug companies across both sides of the Atlantic are seeing shares take a hit.He explained: “Pharmaceutical stocks left the FTSE 100 looking sickly on Friday morning as AstraZeneca and GSK shares came under pressure.”The impact on the sector is hard to judge fully at this stage but, at the very least, it will cause a good deal of uncertainty.”The latest UK GDP figures offered evidence of the chilling effect of a Budget build-up filled with warnings about hard decisions. The government’s gloomy messaging proved to be a self-fulfilling prophecy as growth slowed significantly.”Pharma companies are set to open lower when Wall Street markets open, according to pre-market trading ReutersThe former third party candidate is a prominent figure in the anti-vaccine movement. Despite claiming to be supportive of vaccines which are tested and investigated, Kennedy has falsely claimed they cause autism in children.During a 2019 visit to Samoa, the Trump nominee perpetuated allegations that the MMR vaccine was responsible for the death of two infants. Both had actually mistakenly received a muscle relaxant as well as the vaccine.Critics have stated his promotion in vaccine hesitancy in the country contributed to the 2019 Samoa measles outbreak, which killed more than 70 people.Kennedy has also asserted there is no link between AIDS and HIV, argued Chinese and Jewish people are most immune to Covid-19 and claimed a “worm got into my brain and ate a portion of it”.