Evaluation of immunogenicity and safety of the subjects aged 60 years and above with chronic bronchitis and chronic obstructive pulmonary disease recruited to receive the schedule of three doses of inactivated COVID-19 vaccine on day 0, day 21 and day 111, respectively .

The subjects aged 60 years and above with chronic bronchitis and chronic obstructive pulmonary disease were recruited to receive three doses of inactivated COVID-19 vaccine on day 0, day 21 and day 111, respectively.

Blood samples were collected before the first dose, 28 days after the second dose, before the third dose, 28 days after the third dose and 6 months after the third dose, respectively.

Any local or systemic adverse events that occurred within 21/28 days after vaccination will be recorded.

Inclusion criteria:

• Subjects aged 60 and above with full capacity for civil conduct;
• Chronic bronchitis (or chronic obstructive pulmonary disease) diagnosed by a medical institution at level I or above;
• Body temperature < 37.3 ° C confirmed by clinical examination before enrollment ;
• Able and willing to complete the entire study plan during the study follow-up period;
• Have the ability to understand the study procedures, voluntarily sign informed consent, and comply with the requirements of the clinical study protocol

Exclusion criteria for the first dose::

• Subjects were previously confirmed cases of COVID-19 or asymptomatic infected persons;
• Subjects have history of vaccination against COVID-19;
• Being allergic to any component of vaccines (including excipients) ;
• Injection of non-specific immunoglobulin within 1 month before enrollment;
• Injection of live attenuated vaccines within 1 month and injection of other vaccines within 14 days before enrollment;
• Subjects who have experienced severe allergic reactions to vaccines (e.g. acute anaphylaxis, urticaria, angoneeurotic edema, dyspnea, etc.);
• Having uncontrolled epilepsy and other progressive neurological disorders and a history of Guillain-Barre syndrome;
• Having severe liver and kidney diseases, malignant tumors, acute diseases or acute episodes of chronic diseases;
• Have been diagnosed with congenital or acquired immunodeficiency, HIV infection, lymphoma, leukaemia or other autoimmune diseases;
• Have been diagnosed with thrombocytopenia or other clotting disorders that may contraindicate subcutaneous injection;
• During an acute episode of chronic bronchitis/chronic obstructive pulmonary disease;
• Other subjects whose physical conditions, as determined by the investigator, are not suitable for inclusion in clinical studies.

Exclusion criteria for the second dose:

• Subjects who had vaccine-related adverse reactions after the first dose;
• Having high fever (axillary temperature ≥39.0℃) for three days after the first dose of inoculation, or severe allergic reaction;
• Having any adverse nervous system reaction after the first dose;
• During the acute onset of a chronic disease, or the recovery of acute complications less than two weeks;
• Other reasons for exclusion considered by the investigator.