WASHINGTON (AP) _ President Reagan is under heavy pressure from doctors, drug makers and parents to sign legislation that would bypass the courts and set up a federal fund for children injured by vaccinations.

Approved by Congress just before adjournment, the measure results from a nationwide campaign in 1978 that ushered in strict enforcement of state laws requiring immunization. It also resulted in increased injuries to children.

Fifty to 75 youngsters each year out of millions vaccinated suffer permanent neurological damage as a result of vaccines, mainly the variety aimed at pertussis, or whooping cough, the American Academy of Pediatrics says.

The Reagan administration has opposed proposals similar to the current one. But Justice Department spokesman Pat Korten said late Monday it is still deciding what recommendation to make to the president.

The measure would cost $67 million annually, and only part of that would be paid through a surcharge of 10 cents to $1.50 on vaccine doses.

In opposing earlier versions of the plan, the administration said the surcharge represented a new tax and therefore should be defeated. It also expressed fear that the proposal would bring makers of lawn mowers, hair driers and others involved in product liability legislation to Washington in quest of a victim compensation fund.

Doctor groups, pharmaceutical houses and parents supporting the legislation were planning a news conference today as they sought to build pressure on the administration.

Barbara Loe Fisher, head of Parents Dissatisfied Together, a group formed to push for the measure, said a 10-year-old Florida youngster, Stacey Scholl, who was injured by a vaccination, will appeal to President Reagan to sign the bill.

Parents also have mounted letter writing and telegram campaigns to urge Reagan to sign the bill co-sponsored in the Senate by Sens. Orrin Hatch, R- Utah, and Sen. Edward M. Kennedy, D-Mass.

''Parents are getting desperate,’' Mrs. Fisher said. ''They want to take care of their kids and they’re worried about what’s going to happen after they die, because, basically, there’s no way financially to get them into an institution.’'

The measure would affect cases arising from immunization with DPT vaccine for diphtheria, pertussis and tetanustsis as well as polio vaccine and MMR vaccine for measles, mumps and rubella. They are the vaccines required in most states for entry into school.

According to Jackie Noyes, director of government relations for the American Academy of Pediatrics, the pertussis vaccine causes an adverse reaction once in each 310,000 doses. Polio vaccine results in damage in one in 5 million cases and measles, mumps in rubella vaccine even less frequently.

Under the bill, a no-fault system would be established under jurisdiction of federal courts. Compensation will be awarded for medical, rehabilitation costs and projected lost wages not covered by insurance.

The program will make a payment of up to $250,000 for pain and suffering or a fixed death benefit of the same amount. It also will pay ''reasonable’’ attorneys fees.

Those who suffer injury, and their families, must enter the no-fault program before filing suit. If they are offered a payment under the program, they must then decide whether to accept or file suit. Those who accept will surrender their right to go to court.

Trials will be divided into three separate proceedings to determine liability, then compensatory damages and finally punitive damages.

The feature was designed ''so that the evidence on the extent of the plaintiff’s injury or on the actions of the defendant that allegedly justify punitive damages does not prejudice the findings as to causation and fault,’' according to a fact sheet provided by the American Academy of Pediatrics, which supports the legislation.

If families are dissatisfied with the offer under the no-fault system and go to court, they will face liability rules modified under the legislation.

Manufacturers will not be liable for unavoidable side effects of their vaccines if they are prepared properly and accompanied by adequate directions and warnings. The court will with some exceptions presume that directions and warnings are adequate if they have approval from the Food and Drug Administration.

Vaccine manufacturers cannot be held liable solely for failing to provide warnings directly to vaccine recipients rather than physicians. This would overrule a number of federal court findings.

Manufacturers will be protected against punitive damages if they show its product complied with FDA requirements unless the company engaged in wrongful or criminal misconduct involving the vaccine.