Malaysia's hopes of achieving herd immunity by the end of this year could be dashed by its senior citizens, many of whom have been slow to register for the second phase of inoculations set to kick off next month.

The country is on track to finish inoculating more than 500,000 front-liners just over one month after the arrival of the first batch of Covid-19 vaccines.

Phase two, slated to run from next month to August, targets senior citizens aged 60 and above, and other high-risk groups.

However, there are concerns about the low registration rate for voluntary vaccination among Malaysia's 9.4 million senior citizens, who account for around 30 per cent of the population.

In Selangor, Malaysia's most developed state, 90 per cent of the elderly citizens have yet to register for vaccination, according to the state's Covid-19 task force chairman, Datuk Seri Dzulkefly Ahmad.

Malaysians have been encouraged to register for vaccination via the MySejahtera contact tracing app, which has 21 million users, more than half of the population.

They can register online as well. But a lack of access to the Internet and knowledge of how to use online services have left many senior citizens in the lurch.

Without access to reliable information regarding the vaccine's efficacy, a number of them are also harbouring fears over the potential side effects.

Selangor state assembly member Haniza Talha, along with non-profit organisation Yellow House Kuala Lumpur, on Tuesday kick-started a drive to register senior citizens for vaccinations. But poor turnout over the three days that the campaign ran gave more cause for concern.

"If we have very low numbers of senior citizens registered, I think there will be a delay in delivering the vaccine to the rest of the population," said Ms Haniza, a state assembly member for the Lembah Jaya ward in Selangor.

Ms Shyam Priah, the founder of Yellow House KL, said: "We are a little bit worried because this will cause a bottleneck. If they do not register on time, it will cause a delay for the rest of us."

Aside from a lack of awareness and anxieties over the potential side effects, Ms Shyam said senior citizens also do not see the need to be vaccinated at their age.

"I am not well versed (with smartphones), and I have no one to help me either," said Madam Salfiah Demin, 77, a Selangor resident.

She added that more registration drives are necessary to help senior citizens receive the free vaccines.

Selangor resident Kumarasamy Suppiah, 74, said he registered for the vaccine on Thursday because he did not want to be ruled by fear.

However, he noted that many of his neighbours who are also senior citizens have yet to register. He said the group needs guidance to allay their concerns and convince them to sign up.

Malaysia's coordinating minister for the National Immunisation Programme, Mr Khairy Jamaluddin, previously said the government will reach out to senior citizens through their personal physicians when they visit healthcare facilities for their check-ups and treatments.

Government health clinics have been providing senior citizens with information on the vaccination programme and are helping to register them during regular medical visits.

There are currently five ways to register for the Covid-19 vaccines, including through MySejahtera and a government website. They can also register via a hotline, at public health clinics and through outreach programmes.

Malaysia aims to vaccinate 80 per cent of its population by the end of this year through its immunisation programme.