Why it is important to vaccinate a human newborn within 24 hours since birth?

Question

In Poland a newborn has to be vaccinated within 24 hours against hepatitis B and tuberculosis.

As I understand it is good to be vaccinated against both, I do not see the need to hurry so much. Hepatitis B is transmitted sexually or by blood. The former vector is definitively unsuitable for a newborn, and the latter... Well, I do hope so far all Polish hospital adapted to Ignaz Sammelweis advice on antiseptics. In case of BCG vaccine against tuberculosis (containing alive bacteria) there would be an additional risk if the newborn's immune system were in any way impaired which is unknown within first 24h. It is not that tuberculosis is common disease in Poland - is endemic (probably due to the obligatory vaccination indeed).

What possible biological benefits are there to vaccinate a newborn so early? Especially which of them prevail over possible risks of BCG vaccination?

Answer 1

In the US, infants are vaccinated against Hep B at birth and again a month or two later as well, because of the risk of maternal transmission. If the mother is known to be HepB positive, HBIG will also be administered.

Perinatal HBV transmission can be prevented by identifying HBV-infected (i.e., hepatitis B surface antigen [HBsAg]-positive) pregnant women and providing hepatitis B immune globulin and hepatitis B vaccine to their infants within 12 hours of birth.

The reason for the HBIG is obvious, but it doesn't last for life. Therefore, the vaccine and its booster.

Hepatitis B virus (HBV) infection in a pregnant woman poses a serious risk to her infant at birth. Without postexposure immunoprophylaxis, approximately 40% of infants born to HBV-infected mothers in the United States will develop chronic HBV infection, approximately one-fourth of whom will eventually die from chronic liver disease.

In countries where HepB is not prevalent, there is little cause to immunize at birth. However, it is too common in the US.

Preventing perinatal HBV transmission is an integral part of the national strategy to eliminate hepatitis B in the United States. National guidelines call for the following:
- Universal screening of pregnant women for HBsAg during each pregnancy
- Case management of HBsAg-positive mothers and their infants
- Provision of immunoprophylaxis for infants born to infected mothers, including hepatitis B vaccine and hepatitis B immune globulin
-Routine vaccination of all infants with the hepatitis B vaccine series, with the first dose administered at birth

The risk of HepB vaccine is low. The seriousness of the disease is high. It is not only the mother who might be a carrier. There are many unidentified carriers in the US. That makes the risk-to-benefit ratio low. Driving your newborn home in an automobile is probably more of a risk than the vaccine, but most people do so anyway, and do so many, many times over the course of the baby's life.

In the US, we do not routinely vaccinate against TB, so I cannot address that issue with any degree of expertise. The risk-to-benefit ratio is not as low as for HepB. It is given to children who are continuously exposed to someone (say, a parent) with active TB, or in certain communities where TB is very prevalent. Obviously, if the risk of SCID (severe combined immunodefficiency) is high, the risk of the vaccine is much higher, and some infants have died from it.

Discussing the risk to benefit ratio of all infant vaccines is too broad for this venue.

_{Separating Fact from Fiction in the Newborn Nursery: Hepatitis B Vaccine for Newborns
The benefits and risks of bacille Calmette-Guérin vaccination among infants at high risk for both tuberculosis and severe combined immunodeficiency: assessment by Markov model}

Answer 2

Since another posted answer addresses HepB vaccination at least as effectively as I would have, I'll say something about first-day scheduling for BCG, which is consistent with WHO guidelines (emphasis added):

In countries with a high burden of TB, a single dose of BCG vaccine should be given to all infants as soon as possible after birth. Since severe adverse effects of BCG vaccination are extremely rare even in asymptomatic, HIV-positive infants, all healthy neonates should be BCG-vaccinated, even in areas endemic for HIV ...

(it goes on to discuss recommendations for symptomatic HIV-positive infants. I didn't look at the details of the Polish vaccine policies, but I'd be extremely surprised if there weren't an exception/variation for newborns who are known to be immunocompromised. We can argue about the frequency of newborns who are immunocompromised based on factors that are unknown before birth [i.e. not based on known factors such as genetics, mother's condition, etc.] ...)

I'm admittedly speculating a bit here, but based on what I've read it seems that the main reasons for "as soon as possible after birth" are (1) to allow for development of immunity and (2) logistics, i.e. increasing the actual coverage achieved.

Development of immunity: it takes time for immunity to develop, so the issue is not that babies will be exposed to Tb in the hospital, but that they may be exposed before the vaccine has taken effect. Gaisford and Griffith 1951 quote Wallgren (1950) as saying that effective immunity may be delayed by 10-12 weeks. More recently, Saroha et al 2015 say

BCG vaccine induces delayed type of hypersensitivity reaction and cell mediated immunity (CMI) in the host 4–8 weeks after immunization.

Logistics: Oberoi et al. 2017 report on changing scheduling of BCG vaccination in Indian clinics:

Rescheduling of BCG dose, from twice weekly to daily, the coverage of BCG and OPV zero dose increased from 54% (in 2014) to 78% (in 2015), and a marked increase from 8.2% to 42.9% was noted for the birth dose of hepatitis B.

Is Poland a high-incidence Tb country?

• Tb incidence in Poland in 2016 was about 18 per 100,000: based on this map, that's about twice the level of most Western European countries (and more than triple the rate of Canada, which is what's referenced in the link you give above about dangers to immunocompromised people), but half to a third of levels in the former Soviet Union ...
• The World BCG Atlas shows that vaccine policies follow a similar geographic pattern - BCG is used in Eastern but not in most of Western Europe

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• the rate of adverse advents following BCG vaccination in Poland is low and hasn't changed much after changes in timing of vaccination:

It is generally estimated that local adverse reactions usually occur at the rate of 0.1 to 0.5 per 1000 vaccinations, and serious disseminated complications occur at rate of less than 1 in a million vaccinations

• Some research studies suggest that delaying vaccination for a few weeks may have different (better or worse) effects (e.g. here, here).