Necrotizing enterocolitis, usually called NEC, is a condition where the intestines become infected and can begin to die. The disease usually affects premature babies, although term babies may also get NEC. Necrotizing enterocolitis is a serious condition that may require surgery, and has a high morbidity and mortality rate.
Bordetella vaccines are given to puppies at about 12 to 18 weeks. According to Doodle Dog Shop the Bardatella vaccine is optional at 6-8 weeks. There are three year rated rabies virus such as Imrab-1 that can be given to puppies at twelve to sixteen weeks as well.
The time of effectiveness on vaccines is a controversial issue. Some believe that vaccines in fact can last the entire dog's life. But it's recommended to get yearly boosters on most vaccines, 3-year booster on some rabies vaccines, and 6-month boosters on certain bordatella vaccines. If it's not required, then I wouldn't worry about it since it's only been about 3-4 months.