After giving informed consent, patients with hypertension, patients with diabetes, patients with both diseases, and healthy controls, all aged 60 years or older, are given a third doses of the inactivated SARS-CoV-2 vaccine (Vero cells).~These subjects are all from the COVAX (HT/DM)-Wuhan clinical trial (NCT05065892). 50% of them receive the booster vaccine 3 months after the second dose (0-1-4 schedule); 50% of them receive the booster vaccine 5 months after the second dose (0-1-6 schedule).~Venous blood samples are collected before the booster dose and on day 28 after the booster dose to evaluate the immunogenicity of the vaccine.~Venous blood samples are also collected on day 84/168/252/336 after the booster dose to evaluate the antibody persistence of the vaccine.~Adverse events are actively recorded on a diary card once daily from day 0 to day 7 and once from day 8 to day 21 after the booster dose. Serious adverse events (SAE) are collected within 6 months after the booster dose.
To evaluate the post-marketing immunogenicity, safety and antibody persistence of the third dose (booster) of Covid-19 vaccine in patients aged 60 years or older with hypertension and/or diabetes.