Almost half of the 664 respondents aged 60 and above polled had misconceptions that the coronavirus will become weaker and 30 percent believed it would become less infectious.

Some 90 percent thought "young seniors" of between 60 and 69 years old are not in the high-risk group while half see people with "three highs" in blood pressure, fat and sugar levels as not in that category too.

Of the 18 percent who haven't got the third dose, 70 percent worried about vaccine safety, and over half thought they would still get infected even if they got vaccinated.

The Patients and Medical Professionals Rights Association said the rate of adverse events after receiving the two types of vaccines was only about 40 per 100,000 cases here, which is very rare, and there is no evidence that the higher the vaccine efficiency, the greater the side-effects.

Infectious disease expert Joseph Tsang Kai-yan said experts thought mixing vaccines is safe and effective and the elderly should not wait for next-generation vaccines.

He said the current dominant BA.5 Omicron subvariant is 35 percent more infectious than BA.2 and can replicate in the lungs 34 times more effectively.

The association also said the outreach program should be reviewed, especially the provision of two vaccine options for care homes, so that the elderly can receive higher protection against the new wave.

That came as vaccination centers saw more toddlers.

"About 600 to 700 children were getting vaccinated everyday, and that increased to about 1,600 yesterday," said Samuel Kwok Po-yin, operator of vaccine administration at Kwun Chung Sports Centre.

But the first-dose rate for children under three years old remains around only 23 percent.