I used the main guide for all of the other diseases, but now that Shadow Plague is out you will need to do this scenario with that disease too. Here is my guide for 3 Biohazards on Shut Down Everything with Shadow Plague
Genes: Brawler, Budget Bat, Aerocyte, Urbophile, Mad Scientist
Start in the airport in Canada
Evolve Shadow Blessing (Symptoms),
Followed by Lair, Therianthropy, Blood Gift, Dark Cloud (Vampires)
Moving Vampire: Use slow speed if needed, move vampire and move vampire again within MAXIMUM 2 days of reaching new country, if you have country selected before arrival then you will see the 'Infected' number tick up and up, after 2 ticks, then move again.
Move Vampire to Florida tip of USA (Nearest Caribbean)
Create Lair in USA
Move to Caribbean, Mexico, Central America, Eastern Point of Colombia
Evolve Droplets 1 when DNA (Transmissions)
Move to Eastern Point of Brazil
Evolve Shadow Trail (Symptoms), Travel Speed 1 (Vampire) when DNA
Move to the Port of West Africa
Create Lair in West Africa
Move to Bottom of Central Africa, Botswana, Angola, Zimbabwe, South Africa, Top of Madagascar
Evolve Fomites 1 (Transmissions) when enough DNA
Move to the Top of East Africa, Sudan, Egypt, Middle East, Saudi Arabia,
Evolve Corrupted Air (Vampires) when enough DNA
Move to Iraq, Iran, Pakistan, India, (all straight line east)
Move to Afghanistan, Central Asia, Kazakhstan, Russia, (all straight line north)
Create Lair in Russia,
Move to China, Bottom of S.E. Asia
Evolve Shadow Portal (Vampires) when enough DNA
Move to Indonesia, Australia, North of NZ
Evolve Droplets 2 (Transmissions) when enough DNA
Move to Top of New Guinea, Top of Philippines, Teleport to Russia (Lair) to point nearest Korea/Japan, Korea, Japan
Teleport to Russia (Lair), Finland Border, Finland, Sweden, Norway, UK, Spain, France, Italy, Central Europe, Germany, Poland, Baltic States
SAVE HERE, At this point you should not have had the Templars show up if you haven't stayed anywhere for more than 2 days, if you save here you can reload until you get a favourable Templar distribution when they turn up.
Evolve as much of this chain as possible, do the rest when enough DNA: Nocturnal, Anaemia, Pallor, Weeping Sores, Hyperdontia, Jugular Bite, Shadow Slaves, Muscular Hypotrophy, Masticatory Tension, Photophobia, Pheromone Secretion, Anabolic Boost,
Move to Ukraine, Balkan States, Turkey,
Teleport to USA (Top Right), Move to Canada (Top Right), Greenland, Iceland,
OPTIONAL: At this point I used Vampiric Awakening (Symptoms, creates another Vampire) to help take out the Labs/Templars quicker, however it means trying to handle 2 vampires so you can leave this out if you wish
FiNAL STAGE: Evolve these when possible: Blood Rage, Adrenal Surge, Dark Infiltration, Shadow Blades, Demonic Fury, Lair Healing 1
Fight off the labs with the most priority, fight off the Templars using Blood Rage, co-ordinate your vampires to take out the Templars most efficiently, Be aware of your vampires health and move back to other countries to regain health, Evolve Dark Ritual as well to heal very quickly in Lair countries.
Once the labs are clear and Templars are dead move your vampires to countries with the least infected (Just being in a country will heavily increase the number affected.
Bear in mind also that there are a couple of countries in South America and Northern Africa that you haven't infected, so if they don't get infected naturally make sure you move a vampire there.
This final stage all happens very quickly so pause every day or every other day to move vampires and check countries that are infected least.
Utilise the lairs for movement, one will probably get taken out by drones so bear that in mind when they start attacking it.
Use blood rage wherever possible as it is free and helps heal the vampire and increase infection.
Final tip is to evolve the Drug ability in Vampires if you have some leftover DNA as well as Blood Sacrifice 1 and 2
This method got me to about 63000 the first time, then keep reloading your save and tweaking it to where the Templars surface etc to get you over the required score, took me about 10 retries.