Councils should be able to stop anti-vaccination protesters from demonstrating outside schools by using exclusion orders, Labour leader Sir Keir Starmer has said.
Sir Keir said it was "sickening" that protesters were spreading "dangerous misinformation" to children.
He urged the government to "urgently" update the law so exclusion zones can be rapidly set up around school gates.
Ministers have also expressed concern about such protests.
Home Secretary Priti Patel said freedom to protest was a fundamental part of democracy, but told the Daily Telegraph: "It is completely unacceptable for children, teachers, or parents to be intimidated and harassed outside their school by protesters peddling misinformation and dangerous lies about the life-saving vaccine programme."
Almost eight in 10 schools said they had been targeted by anti-vaccine protesters in a recent survey by the Association of School and College Leaders (ASCL) union.
Most of this had been through emails threatening legal action, but the ASCL said in some cases staff had been threatened with physical harm and on other occasions protesters had gained access to school sites.
Earlier this month, a head teacher at a school in Gateshead said anti-vaccine protesters had left students distressed after showing them pictures of what appeared to be dead children.
Sir Keir, who is a former director of public prosecutions, said local authorities should have the power to impose public spaces protection orders immediately, if agreed by the school, leader of the council, and local police chief constable.
Such orders have been used previously to move on protesters outside abortion clinics, but often are time-consuming to set up.
Labour said the fast-track orders could be in place within five days and stay in place for six months.
Sir Keir said: "The uptake of vaccines among children is far too low and the government's rollout is painfully slow. Everything must be done to get those eligible jabbed as quickly as possible in this public health emergency."
By Rachel Schraer, BBC Reality Check Health Disinformation Reporter
Anti-Covid vaccine protests have been reported across Britain - from Glasgow, Cardiff, London and Manchester to Dorset, Telford and Leicester.
Those gathering outside schools think it's wrong to vaccinate children, while some hold wilder unfounded beliefs - such as that the whole pandemic is a hoax.
The ASCL found at least 420 schools had experienced protests, showing it's not a fringe concern.
But a large number of protests appear to stem from just a couple of groups on the encrypted messaging app Telegram.
One organiser said she had visited every secondary school in Hartlepool, while another group can be seen coordinating multiple school visits a day from Kent to Cheshire.
As well as targeting teachers with sham legal documents, groups organise to hand leaflets out to children featuring QR codes which lead to extremist and conspiracy content.
As pressure mounts to protect pupils from being harassed outside schools, there is growing discussion on some of these platforms of strategies to intercept children further away from school, walking home or on their way to the bus stop.
Geoff Barton, general secretary of the ASCL union, said schools were already "under great pressure" because of disruption from the pandemic and "the last thing they need is the additional problem of protesters outside their gates".
Covid vaccines were key to keeping students at school, he said, adding: "If protesters think otherwise, there are plenty of outlets for them to express their views without resorting to targeting schools."
The ASCL previously said that of the 526 responses from schools eligible for the Covid vaccine programme for 12 to 15-year-olds, 13% had reported seeing demonstrators immediately outside their school. One in five reported protesters in the local area.
Some 18 schools said demonstrators had gained access to the school and protested inside the premises, and 20 said they had received communications threatening physical harm to staff.