I’m sorry, your poor husband.
My very fit and healthy SIL (ex Olympian) had the vaccine and then got two blood clots, one on each lung, the NHS told him it was coincidence, he eventually sought treatment at the American hospital in Cheshire, he was told to never have another Covid vaccine, his private health wouldn’t cover him because he had received the vaccine and they classed it as experimental medicine.
Here is some information from AI but there are lots of articles for and against.
The most serious side effects of COVID-19 vaccines are rare and include anaphylaxis, myocarditis, Guillain-Barré syndrome, and certain rare blood clotting issues.
GOV.UK
Serious Side Effects
Anaphylaxis: A severe, life-threatening allergic reaction that causes swelling, hives, and low blood pressure. It occurs in about 5 out of every 1 million people and usually happens within minutes of the shot, which is why clinics ask you to wait 15 minutes after vaccination.
Mayo Clinic
+1
Myocarditis and Pericarditis: Inflammation of the heart muscle (myocarditis) or the outer lining of the heart (pericarditis). These are rare and most often affect adolescent and young adult males after receiving an mRNA vaccine (like Pfizer or Moderna), usually within a week. Most people recover quickly with rest and basic treatment.
nhs.uk
+3
Guillain-Barré Syndrome (GBS): A rare nervous system disorder where the immune system damages nerve cells, causing muscle weakness. It has been reported in very rare cases, particularly linked to viral-vector vaccines like AstraZeneca.
Health New Zealand | Te Whatu Ora
+2
Thrombosis with Thrombocytopenia Syndrome (TTS): A rare condition involving serious blood clots with low blood platelets. This was primarily associated with adenovirus-vector vaccines (such as Johnson & Johnson and AstraZeneca) rather than mRNA vaccines.